Andrew Leach's explanation is sound as far as how you might go about doing this, but the answers all sound awkward and goofy. I think this points to a bigger point that you shouldn't do this.
Consider the reasons for using passive voice. The whole idea of passive voice is inverting the emphasis between subject and object, so it just doesn't make a whole lot of sense to do in imperative sentences.
Why headlines are the way they are is usually very simple:
- They need to be concise (there is limited space)
- They need to be catchy (make people want to read the article)
There are two possible sentences that could have lead to this headline:
The Government has asked about the safety of the northeast community.
The Government has been asked about the safety of the northeast community.
Obviously all the articles were dropped, and part of the verb. Also, the word government has been abbreviated. This definitely makes the headline more concise.
Now, you are observing very correctly, we do no longer know if the government was asked, or if they did the asking. You will have to read the article to be sure. And hey, that is what the headline maker wanted: make you read the article. So, this headline is successful on both counts!
Now, even without reading the article, we can make an educated guess as to who did the asking.
If the government would be doing the asking, I would assume a present tense. After all, if the government asked something, and they have answers, I would not expect to be informed about their asking, I would expect to be informed about what they are doing or have done with the answer that they got. Of course, if someone has claimed tat they did not show any interest, it might be news-worthy to tell us that they asked.
However, if the government is asking now, the headline could simply sate "Govt. asks", even shorter than it is now.
So, without being able to be sure without reading the article, I would guess that someone, or some organisation asked the government about a situation; the implication being that the government now finds itself obliged to come up with information that it did not earlier share on its own accord.
Best Answer
If the only direction for answering this question is to choose the best fit for the blank in the sentence, then I have to agree with you that B) is the answer.
Both C) and D) result in grammatical errors. C) results in a subject that's missing a verb, and D) results in a verb that's missing a subject. We can easily ignore those possibilities.
Both A) and B) result in grammatically sound sentences. "Floated" could be the simple past tense form, or it could be the so-called past participle form. "Floating" could be the so-called present participle form, or it could be the gerund form. The blank in the model sentence can be filled with a participle. If we have to choose only one of these answers, then we have have to look at more than grammatical correctness.
You found a good reference sentence. Tectonic plates float on the molten mantle. This sentence uses the common intransitive sense of the verb "to float", and it employs the active voice. The same structure can be used to describe some of the information in the model sentence: Rubbish floats in the sea.
The verb "to float" also has a transitive sense. In fact, it has more than one. The molten mantle floats the tectonic plates. Children float their toy boats in this pond. We can form passive voice sentences from the information in these active voice statements: Tectonic plates are floated by the mantle. Toy boats are floated by children.
We cannot choose between A) and B) on the basis of which voice makes sense. Both voices make sense. The rubbish is floating. The rubbish was floated by someone or something.
I would choose B) because the resulting sentence is less confusing. It is easy to mistake the form "floated" for the simple past tense, since the forms are identical. The passive form implies an unmentioned agent, but no such agent is needed for the model sentence to make sense. The intransitive sense of "to float" is more common. English is my native (and only) language, so I can choose the option which sounds the most natural.
If I had to choose only one answer, I'd choose B) as the best answer. If I had to choose all applicable answers, I'd choose both A) and B) as correct answers. I don't see any way to eliminate B) as a valid choice.