True about scurvy is:
**Core Concept**
Scurvy is a disease caused by a deficiency of vitamin C (ascorbic acid) in the diet. It leads to impaired collagen synthesis, which results in connective tissue fragility and various clinical manifestations.
**Why the Correct Answer is Right**
Vitamin C is essential for the hydroxylation of proline and lysine residues in collagen, a process mediated by the enzyme prolyl hydroxylase. Without sufficient vitamin C, collagen synthesis is impaired, leading to the characteristic symptoms of scurvy, including fatigue, malaise, and poor wound healing. Additionally, the impaired collagen synthesis affects the integrity of blood vessels, leading to bleeding gums and easy bruising.
**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because scurvy is not caused by a deficiency of vitamin E, which is an antioxidant involved in protecting cells from oxidative damage.
**Option B:** This option is incorrect because scurvy is not caused by a deficiency of vitamin B12, which is involved in the synthesis of red blood cells and the maintenance of the nervous system.
**Option C:** This option is incorrect because scurvy is not caused by a deficiency of vitamin A, which is essential for vision, immune function, and skin health.
**Clinical Pearl / High-Yield Fact**
Scurvy is a classic example of a disease caused by a nutritional deficiency, and it highlights the importance of a balanced diet in maintaining overall health.
**Correct Answer:** A.