The title is self-explanatory, but what is the appropriate response to "motivate your answer"? Should you prove your answer? Should you just explain it, or give the intuition for it?
For example, suppose students are given a true/false question, and "motivation for the answer" is required. A student could provide a formal, rigorous proof of the answer, which is obviously sufficient, but a student could also give, say, provide a sketch of a graph with an explanation that demonstrates the validity of the answer. Although the latter is not a formal proof, it does point out -albeit, less rigorously - why the answer is correct. Thoughts?