What is an error of commission?

A、An error where one side of a transaction has been recorded in the wrong account, and that account is of the same class as the correct account;

B、An error where a transaction has not been recorded ;

C、An error where one side of a transaction has been recorded in the wrong account, and that account is of a different class to the correct account;

D、An error where the numbers in the posting have been transposed