The correct answer is option 2, Folic acid, which is a vitamin.

To understand why the other options are not vitamins, let`s analyze each of them:

1. Citric acid: Citric acid is a weak organic acid found in citrus fruits like lemons and oranges. While it is important for the production of energy in our bodies, it is not classified as a vitamin.

3. Glutamic acid: Glutamic acid is an amino acid that acts as a neurotransmitter in the brain. It is not considered a vitamin.

4. Linoleic acid: Linoleic acid is an essential fatty acid that our bodies cannot produce on their own, meaning we need to obtain it from our diet. However, it is not classified as a vitamin.

On the other hand, folic acid, which is option 2, is a B-vitamin that is essential for various important functions in our bodies. It is particularly vital for cell division and DNA synthesis. Folic acid is commonly found in foods like leafy green vegetables, legumes, and fortified grains.