A school bus with red lights flashing and stop arm extended:
Correct. Red flashers + stop arm = required stop for approaching traffic in both directions (with the divided-highway exception in some states).
CDL Practice Question #482
Category: School Bus
Why this question matters
This question is one of 55 in our School Bus bank. The reasoning above comes directly from the AAMVA CDL Manual, the source document used by every U.S. state DMV. Memorizing the underlying rule — not just the letter answer — is what separates passing on the first attempt from a return trip and another fee.