The correct option is
A Various aspects of insects
Entomology is the scientific study of insects, a branch of zoology.
Entomology is a taxon-based category; any form of scientific study in which there is a focus on insect-related inquiries. It included the study of terrestrial animals in other arthropod groups or other phyla, such as arachnids, myriapods, earthworms, land snails, and slugs. Hence, entomology is the study of various aspects of insects.
So, the correct answer is 'various aspects of insects'.