Debt Ratings Issued by Companies Such as Moody's and Standard

Debt ratings issued by companies such as Moody's and Standard and Poor's depend on:

A) the probability of firm default and protection given in the indenture in case of default.
B) how large the company is and the number of restrictive covenants.
C) the size of the fee paid by the issuer and their industry.
D) the issue size,type of issue and their industry.
E) None of the above.