Which one of the following vitamins is known as the anti-sterility factor because its deficiency is associated with reproductive problems in experimental animals?

Introduction:
Vitamins often have descriptive names based on their major physiological roles or the diseases caused by their deficiency. One of these vitamins has been called the anti-sterility factor because early experiments showed that its deficiency caused reproductive failure in animals. This question asks you to identify which vitamin carries this label in classical nutrition literature.

Given Data / Assumptions:
- The term to be matched is anti-sterility factor. - The options include ascorbic acid (vitamin C), tocopherol (vitamin E), riboflavin (vitamin B2) and niacin (vitamin B3). - We assume animal experiments where deficiency signs were first observed. - The focus is on the vitamin most strongly associated with reproductive health in this classical sense.

Concept / Approach:
Vitamin E, whose most common form is alpha-tocopherol, was discovered in studies where rats fed vitamin E deficient diets became sterile. Restoration of vitamin E resolved the reproductive issues, leading researchers to refer to it as an anti-sterility vitamin. While vitamin E has broader antioxidant roles in humans, this name stuck in many textbooks. Vitamins C, B2 and B3 are associated with other deficiency diseases such as scurvy, ariboflavinosis and pellagra, respectively, and are not primarily labelled as anti-sterility factors.

Step-by-Step Solution:
Step 1: Recall that vitamin E is fat soluble and acts mainly as an antioxidant protecting cell membranes. Step 2: Remember that early vitamin E deficiency experiments in rats showed degeneration of reproductive organs and sterility. Step 3: Connect this with the label anti-sterility factor applied to vitamin E in classical nutrition texts. Step 4: Review the roles of vitamins C, B2 and B3 and note that their classical deficiency diseases are scurvy, glossitis and pellagra, not primarily sterility. Step 5: Choose tocopherol (vitamin E) as the vitamin known as the anti-sterility factor.

Verification / Alternative check:
Standard biochemistry and nutrition textbooks state that the name tocopherol is derived from Greek words meaning childbirth and bearing, reflecting its early association with fertility. They explicitly refer to vitamin E as an anti-sterility vitamin based on animal studies. Although in humans the deficiency picture is broader and includes neuromuscular problems, the historical naming remains widely taught. This confirms vitamin E as the correct answer.

Why Other Options Are Wrong:
Ascorbic acid (Vitamin C): Known as the anti-scorbutic vitamin because its deficiency causes scurvy, characterised by bleeding gums and poor wound healing, not primarily sterility. Riboflavin (Vitamin B2): Deficiency leads to ariboflavinosis with symptoms like sore tongue, dermatitis and eye problems; it is not chiefly linked with sterility. Niacin (Vitamin B3): Deficiency causes pellagra, characterised by dermatitis, diarrhoea and dementia, rather than reproductive failure as the main sign.

Common Pitfalls:
Some learners mix up vitamins E and A because both are fat soluble and important for reproductive and visual health, respectively. Another error is to assume that anti-sterility refers to any vitamin affecting general health, which could be many. The key is to remember that vitamin E was discovered in the context of fertility experiments and that its name tocopherol directly hints at childbirth, making it the classical anti-sterility factor in nutrition.

Final Answer:
The vitamin known as the anti-sterility factor is Tocopherol (Vitamin E).