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.

Support tranches are most appropriate for investors who are:
Option A:concerned about their exposure to extension risk.
Option B:concerned about their exposure to concentration risk.
Option C:willing to accept prepayment risk in exchange for higher returns.

Answer: C