Among the following vitamins, which one is especially sensitive to heat and is most easily destroyed during prolonged cooking, boiling, or food processing?

Introduction / Context:
Vitamins are essential micronutrients that the human body needs in small amounts for normal growth, immunity, and metabolism. Some vitamins are stable under heat, while others are easily destroyed during cooking and processing. Nutrition based questions often test which vitamins are heat sensitive, because this affects how food should be prepared to preserve their nutritional value. This question asks which listed vitamin is particularly destroyed by heating.

Given Data / Assumptions:

• The vitamins listed include vitamin E, vitamin C, vitamin A, vitamin B complex, and vitamin K.
• The focus is on destruction by heating during cooking.
• We assume normal household cooking conditions such as boiling, frying, and long simmering.
• We also assume commonly accepted nutritional information about vitamin stability.

Concept / Approach:
Different vitamins have different levels of stability to heat, light, and oxygen. Vitamin C, also known as ascorbic acid, is well known for being highly sensitive to heat, oxidation, and prolonged exposure to air. It is easily destroyed during cooking, especially if foods are boiled for a long time or kept warm for extended periods. Fat soluble vitamins such as A, D, E, and K are comparatively more heat stable under normal cooking temperatures, although they may be lost in frying oils or degraded by very high temperatures. Thus, when the question asks which vitamin is destroyed on heating, vitamin C is the best and most widely accepted answer.

Step-by-Step Solution:
Step 1: Recall that vitamin C is a water soluble vitamin present in citrus fruits, some vegetables, and other fresh foods. Step 2: Remember that vitamin C is easily degraded by heat and long cooking, especially in water where it can leach out and break down. Step 3: Compare this with fat soluble vitamins like A, E, and K, which are relatively more stable at normal cooking temperatures. Step 4: Consider that vitamin B complex members can also be sensitive, but vitamin C is classically cited as the most heat labile in basic nutrition questions. Step 5: Choose vitamin C as the vitamin that is especially prone to destruction when heated.

Verification / Alternative check:
Nutrition guidelines often advise minimal cooking of vitamin C rich foods, such as steaming instead of boiling, and consuming fruits raw to preserve ascorbic acid. Studies show that prolonged boiling can drastically reduce vitamin C content in vegetables. In contrast, vitamins A, E, and K are more resistant to moderate heat; they may be lost with removal of fats or prolonged deep frying, but they are not as immediately destroyed as vitamin C. This repeated emphasis from health and nutrition sources confirms vitamin C as the most correct choice for a heat sensitive vitamin in this question.

Why Other Options Are Wrong:
Option A: Vitamin E is relatively stable to normal cooking temperatures, though it can be affected by high heat and oxidation over time. Option C: Vitamin A has some sensitivity to light and oxidation, but it is more heat stable compared to vitamin C under typical cooking conditions. Option D: Vitamin B complex contains several vitamins, some of which are moderately heat sensitive, but the most classic and strongly heat labile vitamin asked in basic exams is vitamin C. Option E: Vitamin K is fat soluble and generally more resistant to standard cooking temperatures than vitamin C.

Common Pitfalls:
Students may think that all vitamins are equally destroyed by heat or may confuse water solubility with complete heat instability. Another common error is to select any water soluble vitamin, such as a member of the B complex, without recalling that vitamin C is particularly mentioned in textbooks and exam guides as the vitamin most easily destroyed by cooking. To avoid confusion, remember simple rules: vitamin C is extremely sensitive to heat and air, fat soluble vitamins are more stable, and gentle cooking or raw consumption helps preserve vitamin C content in foods.

Final Answer:
The vitamin that is especially sensitive to heat and is easily destroyed on heating is vitamin C.