Vitamin C is also known as ascorbic acid. It is important to note that vitamin C is not an amino acid (option 1). Amino acids are the building blocks of proteins, while vitamin C is a water-soluble vitamin with essential antioxidant properties. Acetic acid (option 3) is a different type of acid commonly found in vinegar and has no relation to vitamin C. Azelaic acid (option 4) is a naturally occurring acid found in wheat, barley, and rye, but it is not another name for vitamin C. Therefore, the correct answer is option 2, ascorbic acid, which is the scientific name for vitamin C.