The correct answer is D. Enlargement of a cervical lymph node to 1 cm in diameter if the diagnosis is otherwise uncertain is a common indication for biopsy. Biopsy is done to obtain tissue samples for examination under a microscope to determine the cause of the lymph node enlargement, such as infection, inflammation, or cancer.
Option A may require incision and drainage rather than a biopsy, and option B is not a common indication for lymph node biopsy. Option C and E are not specific indications for biopsy and do not necessarily require biopsy.