Is there a name for an answer to a question that does nothing but rephrase the question in an answer form?

Solution 1:

I think you might be looking for tautology:

[Tautology] is an argument that utilizes circular reasoning, which means that the conclusion is also its own premise. Typically the premise is simply restated in the conclusion, without adding additional information or clarification.

Solution 2:

Begging the question — An excerpt from this link:

"Begging the question is also known as circular argument, tautology, and petitio principii."

"Here is an example [of begging the question] taken from an article on exclusive men's clubs in San Francisco. In explaining why these clubs have such long waiting lists, Paul B. 'Red' Fay, Jr. (on the roster of three of the clubs) said, 'The reason there's such a big demand is because everyone wants to get in them.' In other words, there is a big demand because there is a big demand."

(H. Kahane and N. Cavender, Logic and Contemporary Rhetoric: The Use of Reason in Everyday Life, 10th ed. Wadsworth, 2006)

Solution 3:

I would call it circular inquiry.