Instructions: In this task, you are given a context and four options. Each option is a suggested ending for the context. You should read the context and pick the best ending for the context. Please answer with "A", "B", "C", and "D".
Input: [header] How to make a heating pad [title] Fill an old sock with uncooked rice. [step] The most simple method for a reusable rice-filled heating pad. It just requires and old sock, some rice, a microwave and something to tie or sew the sock shut. <sep> (A) Be sure it's very dry with a little bit of knot to prevent fraying when it's tewn. [title] Heat the rice material to a comfortable temperature before sticking the heating pad to it. (B) No need to use wood, so long as it's folded closed. [substeps] The extra rice will pass through the tightly sealed parts of the sock. (C) Pre-soaked rice is the best option. [title] Cover the tab that is on the base of the heating pad. (D) First of all get hold a a good sized clean cotton sock that you won't miss, and then pour in the rice. [substeps] There is no fixed amount of rice to use, but it is recommended that the sock be at least half or three quarters full.
Output:
D