Answer: c) genes that have specific DNA structures genes that make molecules of cellular structures.
Explanation:
The structural genes are the form of genes that encode for proteins in the body that are required for performing specialized function in the body of the organism. The proteins are the building blocks of the cells. These genes encodes for the amino acid sequence for the synthesis of protein. These proteins create a physical structure inside the cells of the organism such as cytoskeleton, which gives the cells it's shape.
A gateway substance is something that may be menial but could lead to something bigger, an example is weed in the drugs world, weed is not hard to get and is usually a gateway drug to stronger types of drugs and potentially more dangerous
