Bone healing may be impaired by a. excessive vitamin C. b. nicotine use. c. immobilization. d. a high-protein diet.

b. nicotine use

Explanation:

Studies have shown that smoking reduces the speed at which bones heal from injuries and even though the data is sometimes conflicting, nicotine has been blamed for this impairment.

Vitamins heal bones and so do protein so options a and d are incorrect. Being immobilized gives bones the chance to heal so option c is incorrect as well.

none

explanation:

you did not provide anything to go off of.