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.

In a securitization, time tranching provides investors with the ability to choose between:
Option A:extension and contraction risks.
Option B:senior and subordinated bond classes.
Option C:fully amortizing and partially amortizing loans.

Answer: A