In order to safely aid traffic flow, you should:
a. keep up with traffic even if its faster then speed limit
b. stay to the left if you are traveling slower than the rest of traffic.

In order to safely aid the traffic flow in the U.S roadways a driver should stay to the right lane if you are traveling slower than other cars. You should never try to keep up with faster traffic over the speed limit nor stay to the left. The left lane is used for faster and passing traffic. By staying to the right, you let the faster cars pass you safely. The correct answer should be B.

It means if x is -1 what is y then . check -1 on x axis and then check the value of y when x is -1