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.

The rating agency process whereby the credit ratings on issues are moved up or down from the issuer rating best describes:
Option A:notching.
Option B:pari passu ranking.
Option C:cross-default provisions.

Answer: A