Answer: The right answer is the (D) A declaration or set of rules.
Explanation: Just to elaborate a little on the answer, it can be added that the word doctrine derives from the Latin doctrīna, which has various meanings, such as teaching, instruction, and set of religious, philosophical, or political ideas (or other kinds of ideas) held by a person or a group, such as the Christian doctrine or the legal doctrine, but also set of norms or rules.
