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.

When the collateral manager fails pre-specified risk tests, a CDO is:
Option A:deleveraged by reducing the senior bond class.
Option B:restructured to reduce its most expensive funding source.
Option C:liquidated by paying off the bond classes in order of seniority.

Answer: A