Answer:
B. They determine the structural and functional characteristics of each individual
Step-by-step explanation:
Genes are present in all plants and in all prokaryotes, so answer choices A and E are incorrect. Genes are present in all living things.
Genes do determine the structural characteristics of each individual, but they also determine the functional characteristics.
Structure, which is controlled by genes, directly affects function. For example, a gene could code for a specific protein's structure, which will in turn give it a specific function.
So, the correct answer is B.