Answer:
A: Following the "Golden Rule"
Explanation:
The most appropriate heading for the paragraph is presented in option A: Following the "Golden Rule". Although 'golden rule' means an important principle in a particular situation, the "Golden Rule" is a principle of ethics explained in the Bible, but also taught in other religions: "Do unto others what one would like others did to oneself," which happens to be the mother's "golden rule" too: "be nice to and treat others with respect, etc.