The correct answer is "A)".
Since the value of the dollar has fallen, this means that car producers probably have to spend more money on purchasing raw material and parts from overseas suppliers. As a consequence, in order to keep their same level of profitability, they need to raise the price of the end product, in this case, cars.
This overall scenario makes the automotive not as attractive for investing. This means that the benefits an investor will be missing out if he or she chooses to invest in the car industry over others, in other words, the opportunity cost, have risen.