Which one of the following substances is a true vitamin, sometimes misspelled in the options, and is essential in small amounts for normal human health?

Introduction:
Vitamins are organic compounds required in very small quantities for normal metabolism and health. They cannot usually be synthesised in adequate amounts by the body and must be obtained from the diet. Some common acids found in foods are not vitamins, even though their names may sound similar. This question checks whether you can distinguish a real vitamin from other non vitamin organic acids given in the options.

Given Data / Assumptions:
- The options include citric acid, folic acid (spelled as follic acid in the original question), glutonic acid and none of the above. - We assume standard biochemical definitions of vitamins. - The task is to identify which substance is recognised as a vitamin in human nutrition. - Spelling corrections are applied to clarify the intended compound (folic acid).

Concept / Approach:
Folic acid, also known as vitamin B9, is a water soluble vitamin essential for DNA synthesis, red blood cell formation and proper development of the nervous system in embryos. Deficiency can lead to megaloblastic anaemia and in pregnant women to neural tube defects in the fetus. Citric acid is a weak organic acid found in citrus fruits and is part of the citric acid cycle in metabolism, but it is not classified as a vitamin. Glutonic acid appears to be a misspelling or non standard term; glutamic acid is an amino acid, not a vitamin. Thus, among the options, folic acid is the only true vitamin.

Step-by-Step Solution:
Step 1: Recognise that folic acid is a well known B group vitamin, designated vitamin B9. Step 2: Recall that folic acid is essential during pregnancy and is often recommended as a supplement to prevent neural tube defects. Step 3: Understand that citric acid, although important in the citric acid cycle and present in fruits, is not treated as a vitamin because the body can synthesise and use it as part of normal metabolism. Step 4: Note that glutonic acid is not a standard biochemical name; the closest common compound, glutamic acid, is an amino acid, and amino acids are not vitamins. Step 5: Conclude that folic acid (vitamin B9) is the only correct choice as a vitamin among the listed substances.

Verification / Alternative check:
Nutrition and biochemistry textbooks list folic acid under the B complex vitamins, with detailed descriptions of its structure, sources, recommended daily allowance and deficiency symptoms. Citric acid is discussed in metabolism chapters as an intermediate of the citric acid cycle and as a food additive, but not as a vitamin. Amino acids such as glutamic acid are classified under proteins and amino acid metabolism. None of these non vitamin acids meet the criteria of a vitamin (required in small amounts, not made in sufficient quantities, and causing specific deficiency diseases). This clearly supports folic acid as the correct answer.

Why Other Options Are Wrong:
Citric acid: An organic acid found in citrus fruits and in the citric acid cycle; it is not a vitamin and does not cause a specific deficiency disease when absent from the diet. Glutonic acid: Not a recognised standard compound name; even if it refers to glutamic acid, that is an amino acid and not a vitamin. None of the above: Incorrect because folic acid is definitely a vitamin recognized as vitamin B9 in human nutrition.

Common Pitfalls:
Students may confuse citric acid with vitamin C because both are associated with citrus fruits. However, vitamin C is ascorbic acid, not citric acid. Another pitfall is being misled by spelling errors such as follic acid or glutonic acid and thinking that none of the options is valid. Paying attention to the well known vitamin name folic acid helps avoid this confusion and leads to the correct choice.

Final Answer:
The substance among the options that is a true vitamin is Folic acid (vitamin B9).