Question

Which of the following acids is a vitamin?

• A. Adipic acid
• B. Aspartic acid
• C. Ascorbic acid
• D. Saccharic acid

Hint:

Remember that Vitamin C is also known as Ascorbic acid, and it is an essential nutrient.

Answer 1

The Correct Option is C

Step 1: Understand the definition of a vitamin.

A vitamin is an organic compound that is essential for normal growth and nutrition and is required in small quantities in the diet because it cannot be synthesized by the body.

Step 2: Identify the given acids.

(1) Adipic acid: A dicarboxylic acid used in the production of nylon.
(2) Aspartic acid: An amino acid, a building block of proteins.
(3) Ascorbic acid: Also known as Vitamin C, an essential nutrient.
(4) Saccharic acid: An oxidation product of sugars. 

Step 3: Determine which acid is a vitamin.

Ascorbic acid is the chemical name for Vitamin C, which is an essential vitamin required for various bodily functions, including immune system support and collagen synthesis. 

Step 4: Conclude the answer.

Therefore, the correct answer is (3) Ascorbic acid.

Answer 2

Step 1 — Recognise the common name
The name ascorbic acid is the systematic name for Vitamin C. So option 3 is the likely answer. We explain why the others are not vitamins below.

Step 2 — Short descriptions and roles

• Adipic acid — a dicarboxylic acid (HOOC–(CH₂)₄–COOH) used industrially (e.g. in nylon synthesis). It is not a vitamin.
• Aspartic acid — an α-amino acid (one of the amino acids found in proteins). It is not classified as a vitamin.
• Ascorbic acid — chemically \( \mathrm{C_6H_8O_6} \). It is an essential nutrient for humans (water-soluble vitamin), commonly called Vitamin C. Therefore this is a vitamin.
• Saccharic acid — an oxidation product of sugars (e.g. glucaric acid / saccharic acid), not a vitamin.

Step 3 — Key biochemical roles of ascorbic acid (Vitamin C)

• Acts as a reducing agent (antioxidant) in biological systems.
• Essential for hydroxylation reactions in collagen synthesis (proline & lysine hydroxylation). Without it, collagen formation fails and scurvy results.
• Helps in absorption of non-heme iron from the gut.
• Cofactor for several enzymes (e.g., prolyl hydroxylase).

Step 4 — Deficiency disease 
Deficiency of ascorbic acid leads to scurvy, whose symptoms include bleeding gums, poor wound healing, and weakened connective tissue — demonstrating that ascorbic acid is an essential dietary vitamin.

Step 5 — Chemical formula (LaTeX)
Ascorbic acid: \( \mathrm{C_6H_8O_6} \).

Final answer

Option 3 — Ascorbic acid (Vitamin C).