Which of the following is not a characteristic of bone fractures?
a. a crack or break occurs in the bone.
b. it is caused by a large force or impact on the bone.
c. it does not always include pain.
d. bones naturally begin to heal immediately.

The answer is letter D.

All of the other choices are characteristics of bone fractures. Often bone fractures occur from high impacts or forces inflicted to the bone. Sometime when complete or open fractures occur pain is no longer felt by an individual because of the shock and because of the grave damage it brought to the nerves. 

Bones don't immediately heal but its healing is a natural process in the body that occurs through development of tissues. It usually takes six months to one year to fully mend a broken bone. 

The answer is d because , safety almost always works, to prevent stds and pregnancy