Yellow lighthand signal indicates A. stop B. proceed C. proceed cautiously D. none of the above

The correct answer is C. proceed cautiously.

A yellow light indicates that the light is about to turn red. Drivers should slow down and prepare to stop. If it is safe to do so, drivers may proceed through the intersection before the light turns red. However, they should do so cautiously and be prepared to stop if necessary.

Option A is incorrect because a yellow light does not mean to stop. Option B is incorrect because a yellow light does not mean to proceed. Option D is incorrect because a yellow light does indicate that the light is about to turn red.