In human nutrition, all of the following are fat soluble vitamins except which one that is actually water soluble?

Introduction / Context:
Vitamins are essential micronutrients needed in small amounts for normal metabolism. They are classified as water soluble or fat soluble based on how they are absorbed, transported, and stored. Fat soluble vitamins are stored in body fat and can accumulate, whereas water soluble vitamins are generally not stored in large amounts. This question asks you to identify which listed vitamin is water soluble while the others are fat soluble.

Given Data / Assumptions:

• Fat soluble vitamins include vitamins A, D, E, and K.
• Water soluble vitamins include vitamin C and the B complex group.
• The options list several vitamins by letter.
• We assume standard nutritional classification.

Concept / Approach:
The fat soluble vitamins A, D, E, and K are absorbed along with dietary fat and can be stored in liver and adipose tissue. Vitamin C, also known as ascorbic acid, is water soluble and is not significantly stored; excess amounts are excreted in urine. Therefore, among the listed options, the one that is not fat soluble is vitamin C.

Step-by-Step Solution:
Step 1: Recall the list of fat soluble vitamins as A, D, E, and K. Step 2: Remember that vitamin C belongs to water soluble vitamins. Step 3: Examine the options and note that B, C, D, and E correspond to vitamins commonly taught in nutrition. Step 4: Identify vitamin C as water soluble, while vitamins A, D, E, and K are fat soluble. Step 5: Conclude that vitamin C is the exception among primarily fat soluble vitamin options.

Verification / Alternative check:
Nutritional references classify vitamins A, D, E, and K as fat soluble. Clinical examples include hypervitaminosis A or D due to excessive accumulation, highlighting their storage in body tissues. Vitamin C deficiency leads to scurvy, but because it is water soluble, excess vitamin C is excreted and toxicity is rare compared to fat soluble vitamins. These points confirm the classification.

Why Other Options Are Wrong:
Option B, vitamin D, is fat soluble and involved in calcium homeostasis and bone health. Option C, vitamin A, is fat soluble and important for vision and epithelial health. Option D, vitamin K, is fat soluble and required for normal blood clotting. Option E, vitamin E, is also fat soluble and acts as an antioxidant. None of these are water soluble, so they cannot be the correct exception.

Common Pitfalls:
Students sometimes misremember the list and think that vitamin C might be fat soluble because of its importance. Another pitfall is confusing vitamin C with vitamin E since both have antioxidant roles. It is helpful to remember the group A, D, E, K as fat soluble and that vitamin C belongs with the water soluble group.

Final Answer:
The vitamin that is not fat soluble and is instead water soluble is Vitamin C.