When is a term found in an ancillary document (such as an employee handbook) legally enforceable?

How can you tell that you're driving in the right direction? options are a. there is a white line on your left and a yellow line on your right. b. there are yellow lines on both sides of your vehicle. c. there is a double yellow line on your right. d. there is a yellow line on your left and a white line on your right.