What should you do when approaching a yield sign?

Answer: B — Slow down and proceed with caution.

A yield sign indicates that you must slow down and yield the right of way to other vehicles and pedestrians. It does not necessarily mean that you have to come to a complete stop. Option B is the correct answer because it advises to slow down and proceed with caution, while the other options may be dangerous or incorrect. Option A suggests stopping completely, which is not necessary at a yield sign. Option C suggests speeding up, which goes against the purpose of a yield sign. Option D suggests treating the sign as a stop sign, which is incorrect as a yield sign does not require a complete stop unless traffic conditions require it.