Given a text T, and several options, according to the question posed in the text T to choose the most appropriate option from the options as the answer, please directly output the most appropriate option, do not need to output the explanation.

To determine the price of an option today, the binomial model requires:
Option A:selling one put and buying one offsetting call.
Option B:buying one unit of the underlying and selling one matching call.
Option C:using the risk-free rate to determine the required number of units of the underlying.

Answer: C