When a body part is injured, it should be
a. rested.
b. exercised.
c. stressed.
d. stretched.

When a body part is injured, it should be rested. The correct option among all the options given in the question is option "A". The injured part of the body should never be exercised, stressed or stretched because there is a possibility of the injury getting aggravated. Rest is the best option. So the other options in the question is not at all applicable. A doctor should definitely be consulted before taking any kind of measure except resting. It is important to have a basic knowledge of first aid to deal with minor injuries.