In a formal sense, the conversion of a carboxylic acid to an amide corresponds to which of the following?
A. the combining of the fragments which remain after the loss of -OH from the carboxylic acid and -H from ammonia or an amine
B. the combining of the fragments which remain after the loss of -OH from the carboxylic acid and -H from an alcohol
C. the combining of the fragments which remain after the loss of an oxygen from the carboxylic acid and two hydrogens from ammonia or an amine
D. none of the above