Correct Answer: C

Rationale: The correct answer is C. Maintenance of more than 200 genes is not a function of vitamin A; instead, it is a function of Vitamin D. Vitamin A plays a crucial role in the prevention of night blindness by aiding in the production of the visual pigment rhodopsin. It also supports the growth of soft tissues and bone, as well as the integrity of body openings and their linings. Choice C is incorrect because the maintenance of genes is primarily associated with Vitamin D, not Vitamin A.

Correct Answer: C

Rationale: The first statement is true; the second is false. If a deficiency of one vitamin is suspected, symptoms of other vitamin B deficiencies also may be present. Folate deficiencies usually occur with other nutrient deficiencies. Specifically, folate functions in conjunction with vitamins B12 and C in maintaining normal levels of mature red blood cells.

Correct Answer: C

Rationale: The correct answer is C. Maintenance of more than 200 genes is not a function of vitamin A; instead, it is a function of Vitamin D. Vitamin A plays a crucial role in the prevention of night blindness by aiding in the production of the visual pigment rhodopsin. It also supports the growth of soft tissues and bone, as well as the integrity of body openings and their linings. Choice C is incorrect because the maintenance of genes is primarily associated with Vitamin D, not Vitamin A.

Correct Answer: C

Rationale: While UV radiation can penetrate uncovered skin and convert a precursor of vitamin D to vitamin D3, sunscreen does block the formation of vitamin D3. Sunscreen is recommended by dermatologists to prevent sunburn and reduce the risk of skin cancer. The other choices are correct: the body can produce sufficient vitamin D from sunlight, UV radiation can convert a precursor of vitamin D to vitamin D3, and skin generally produces less vitamin D as a person ages.

Correct Answer: C

Rationale: The statement is correct, but the reason is not correct. A major difference between fat-soluble and water-soluble vitamins is that the body is able to store larger amounts of fat-soluble vitamins. Vitamins A and D are stored for long periods; therefore, minor shortages might not be identified until drastic depletion has occurred. Observable signs and symptoms of a dietary deficiency are often not identified until they are in an advanced state. Water-soluble vitamins, on the other hand, are not stored in the body and are excreted in the urine if taken in excess, making it harder to reach toxic levels.