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 is an example of an affirmative debt covenant? The borrower is:
Option A:prohibited from entering into mergers.
Option B:prevented from issuing excessive additional debt.
Option C:required to perform regular maintenance on equipment pledged as collateral.

Answer: C