To reduce accidents at intersections, a town is considering installing traffic lights with "left turn on green arrow only" signs. Which
measure best determines of the traffic lights and signs are necessary?
A
accidents per unprotected left turn per intersection
B. accidents per intersection
C
accidents per unprotected left turn per driver
D. accidents per intersection per day

A. accidents per unprotected left turn per intersection

Explanation:

The question is asking about "accidents at intersections," so the answer must be related to this.

It is said that accidents happen at intersections because cars coming from different directions are doing different activities. This causes a greater potential to cause an accident. An "unprotected left turn" happens when there is no corresponding light (traffic light) that signals the left turn. This is common among intersections.

The installation of the "left turn green arrow" is helpful for areas with unprotected left turn that may be potential for causing an accident. So among the choices above, letter A (accidents per unprotected left turn per intersection) is the best choice.

answer: the common difference is -0.10

a is the right answer