Please choose the correct ending to complete the given sentence: Health: [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.

Ending1: 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. Ending2: 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. Ending3: Pre-soaked rice is the best option. [title] Cover the tab that is on the base of the heating pad. Ending4: 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.

Answer format: ending1/ending2/ending3/ending4