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.

Which of the following describes a typical feature of a non-agency residential mortgage-backed security (RMBS)?
Option A:Senior\/subordinated structure
Option B:A pool of conforming mortgages as collateral
Option C:A guarantee by a government-sponsored enterprise

Answer: A