What is study of reptiles and amphibians called as ?

Herpetology

The correct answer is Option (3) → Herpetology.

Herpetology is the scientific study of amphibians and reptiles. It encompasses all aspects of their biology, including their evolution, anatomy, physiology, behavior, ecology, and conservation. Herpetology is a branch of zoology, the scientific study of animals.

Histology is the study of tissues. Entomology is the study of insects. Gerontology is the study of aging.