What is the hardest question on the SAT

Idk is this even a question hair smell like poop

The answer is b.i hope this i got the answer from google just to make sure i was correct didnt wanna make you get it

Which of the following is an example of an opposing signal? no examplthates given.   i would say, that traffic lights in a city at major intersections direct the flow of traffic in opposite directions so would be an example.also, stop signs on either side of the same street would be an example. at a train crossing, the light for allowing car traffic in opposite directions or not would be another example.