Given the task definition and input, reply with output. 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 spot signs of illness in parrotlets [title] Check the quality of the feathers. [step] Ruffled, thin, patchy, or dull feathers can be a sign that there is something wrong. A disease or parasite may cause the feathers to fall out or the bird may be plucking them from stress. <sep> (A) Pay attention to only the feathers that are level in color. [substeps] Ruffled feathers are usually the result of overbreeding, parasite control, or another problem. (B) [substeps] If they live alone and pluck their feathers, they may be lonely, not sick! You should still take your parrotlet to the vet, but consider getting them a companion. [title] Examine their skin for swelling or lesions. (C) [substeps] High color and glossy feathers are almost always a sign that something is wrong. The bird may also pick up grain or grain from the feathers. (D) [substeps] If the feathers appear dull and unkempt, the bird may be stressed about something. [title] Check to see if the bird is tall.
B