Plumbing – Bathroom Drain Venting

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I've been trying to figure out the difference between the following solutions. I'm sure that Option 1 is the best, given it's a short direct route to the vent, but I can't justify to myself why the others are bad? From what I can read it's usually the distance from the fixture to the start of the dry vent that matters, not how long the vent itself is.

Given that the sink (where the P trap is located on the right) is too far away from the main vent (far left), what would be the major differences in the following solutions?

(Blue = Vents)
(Black = Drains)

Option 1:
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Option 2:
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Option 3:

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Best Answer

How about this: enter image description here

Or, if permitted by code an air admittance valve (AAV). The AAV is a simple in wall or under sink vent that allows air to vent when needed but blocks water and sewer gas from escaping. Just remember, the AAV must be accessible and are usually covered by an access panel for inspection.

Option #2 is also fine. It's called a "Chicago Loop" and used for sinks on kitchen islands.

Option #3 wont allow the sink to properly vent causing drainage problems.

If that sink is near an exterior wall, you may vent it directly outside, code permitting of course.

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