Answer:
a. vitamin D
b. vitamin C
c. vitamin B3 (niacin)
Step-by-step explanation:
Rickets is a disease affecting children in which their bones are softened and weakened, usually due to an extreme deficiency in vitamin D. Vitamin D is necessary for helping the body absorb calcium and phosphorus, which help to build strong bones.
Scurvy is a disease that can affect a range of age groups from babies to adults, and is caused by a vitamin C deficiency. It can cause the affected person to experience symptoms such as anemia, gum disease, and skin problems. Vitamin C is a critical nutrient for the body to absorb iron and produce collagen, and aids in the growth and healing of body tissues.
Pellagra is a disease caused by a severe lack of a vitamin known as niacin, or B3. It is usually marked by "the four Ds": diarrhea, dermatitis, dementia, and potentially death. Vitamin B3 plays a role in maintaining the body and keeping it healthy, such as by converting nutrients into energy.