Question

You are driving on a road with reversible lanes that are marked with overhead lane signals; choose an answer:

Answer 1

The answer is a. you may drive in a lane under a green arrow.

Overhead lane signals have 2 options. 1) green arrow and 2) red cross. 

Green arrow means driver may use the lane under the signal.
Red arrow means driver must not drive on the lane under the signal.

In the event that the green arrow changes to red cross, you can change lanes and use the one under the new green arrow.