In the doubling-the-angle technique, the vessel takes a first relative bearing of 030° to a lighthouse. The navigator should take the second bearing when the relative bearing to the same lighthouse reads:

Why B is correct

The doubling-the-angle technique requires the second relative bearing to be double the first. Double 030° is 060°. At that second bearing, the distance run between the two observations equals the distance off the object. Bowditch Ch. 7 §703.