Answer:
C) It depends on the value of the Chinese yuan in relation to the dollar.
Step-by-step explanation:
The exchange rate of a currency gives you a nominal value of the local currency against another foreign currency, but just by having a number doesn't mean a lot. First of all we do not know how much can you really buy with 6.42 yuans, so we are not able to know if $1 is cheap or expensive.
Assuming that the price of the horns is competitive, what can really affect this business is the fluctuations of the currency value. If the yuan appreciates against the dollar, the horns will become cheaper, but if the yuan depreciates against the dollar, the horns will become more expensive.