Detailed 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".
Q: [header] How to check lymph nodes [title] Locate your lymph nodes. [step] You have the highest concentration of lymph nodes in your neck, collarbone, armpits, and groin. Once you know where they are, you will be able to check them for pain or swelling. <sep> (A) [substeps] To identify your lymph nodes, look at your earlobe or high neck. To perform a blood test, attach a needle at the corresponding carotid artery. (B) [substeps] Identify them with an eye dropper or a syringe. The eye dropper or syringe should be attached by cord to a length of flexible metal tubing or cleat. (C) [substeps] There are other groups of lymph nodes throughout the body, including the inside of your elbows and knees, but these are not commonly checked for swelling. [title] Test an area with no lymph nodes for comparison. (D) Nodes can be found using this tool : [substeps] Find your very appropriate area of the neck. The most important areas are your lymph nodes, located across the top of your neck.
A:
C