Answer the following question given this paragraph: 

Skeletal system problems include osteoporosis, bone fractures, and ligament sprains. A diet rick in calcium and vitamin D may reduce the risk of osteoporosis and related bone fractures. Following safe practices may also reduce the risk of fractures as well as sprains.


Q: A diet rich in calcium and what vitamin may reduce the risk of osteoporosis and related bone fractures?

 Choices:

- niacin

- vitamin A

- vitamin C

- vitamin d

A:
vitamin d
