Which of the following lists contains only water-soluble vitamins?

The selection of B, consisting of vitamins B and C, is accurate because both of these are categorized as water-soluble vitamins. Water-soluble vitamins are those that dissolve in water and are typically not stored in the body, requiring regular intake through diet to maintain adequate levels.

Vitamin B is actually a complex that includes several vitamins, such as B1 (thiamine), B2 (riboflavin), B3 (niacin), B5 (pantothenic acid), B6 (pyridoxine), B7 (biotin), B9 (folate), and B12 (cobalamin). Vitamin C, also known as ascorbic acid, is essential for various bodily functions, including the synthesis of collagen, absorption of iron, and supporting the immune system.

In contrast, the other options provided contain fat-soluble vitamins. Vitamin A, D, E, and K are all stored in the body's fatty tissues and liver, which is why they do not belong in a list purely containing water-soluble vitamins. Hence, the distinction between the different types of vitamins based on their solubility in water helps clarify why B is the correct listing.