Given the task definition and input, reply with output. In this task, you are given a multiple-choice question and you have to pick the correct option. Answer with option indexes (i.e., "A", "B", "C", and "D").

A frog, in winter, will burrow itself into soft mud, until it freezes, then in the spring (A) it melts, because it is warm-blooded (B) it unfreezes, because it is cold-blooded (C) it remains frozen until it dies (D) it dies, because it is warm-blooded
B