The following diagram represents the structure of a non-essential vitamin - VCE - SSCE Chemistry - Question 14 - 2019 - Paper 1

To determine the classification of this vitamin, we need to analyze its structure shown in the diagram. The structure resembles that of a fat-soluble vitamin, as it contains a large carbon chain typical of such vitamins. Fat-soluble vitamins, such as vitamins A, D, E, and K, are absorbed along with dietary fat and can be stored in the body's fatty tissues.

Thus, we conclude that this vitamin is fat-soluble and can be produced by the human body, which leads us to select option A.