In the Northern Hemisphere, the Coriolis force acts to the right of motion at right angles. If the Coriolis force and the horizontal pressure gradient force are in approximate balance, that means that the PGF must act to the LEFT of the motion (in this case, the wind). Since the PGF is always directed from high to low pressure, this means that the lowest pressure is to your left; to the west. Thus, the answer is (d).