Question

aphthous ulcers are found:
a on the lip.
b in the mouth.
c in the colon.
d in the stomach.

Explanation:

Aphthous ulcers, also known as canker sores, are small, shallow lesions that develop on the soft tissues in the mouth or at the base of the gums. They are not typically found on the lip (as that is more related to cold sores in some cases), in the colon (which may be related to other gastrointestinal ulcers or conditions), or in the stomach (which is related to peptic ulcers).

Answer:

B. in the mouth.