Final answer:
Other drivers should proceed with caution and allow the transit bus to safely merge into traffic when it displays a YIELD sign.
Step-by-step explanation:
When a transit bus displays a YIELD sign and is signaling to enter traffic, it is requesting other drivers to allow it to merge. The appropriate action for other drivers is to proceed with caution and allow the bus to enter the flow of traffic safely. This does not necessarily mean to stop completely, but drivers should be prepared to slow down or adjust their speed to facilitate the bus's entry into traffic. Other drivers should proceed with caution and allow the transit bus to safely merge into traffic when it displays a YIELD sign.