You will be given a definition of a task first, then some input of the task.
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".

[header] How to elevate your hand while sleeping [title] Sleep on your back or side. [step] In order to elevate your hand while you're sleeping, you'll need to sleep on your back or on the side opposite of the arm that needs elevation. This is the easiest resting position for elevating your hand. <sep> (A) [substeps] Lying on your side not only has been shown to help alleviate hand inflation, but it also improves circulation in and around the hand and wrist joints. It's also more efficient than sleeping on your side. (B) [substeps] You can use a pillow to support your arm when you start to feel like your hand's elevating off the ground. Place a rolled up towel over your head to help prevent air from pooling near your arm. (C) [substeps] Sleeping on your stomach won't allow you to elevate your hand as easily. It's much harder to prop it up from behind if you're lying flat on your stomach. (D) [substeps] Lie on your back with the pillow propping your head up at a 45 degree angle. Your dominant hand should support the bottom of your pillow.
Output:
C