Concept:Entomology is the scientific study of insects, including insect pests that affect crops.
Explanation:Crop science has different branches for different problems.
Entomology focuses on insects and their classification, life cycle, behavior, and control.
Pathology deals with plant diseases caused by pathogens.
Zoology is the broad study of animals.
Agronomy deals with crop production and soil management.
Since the question asks about insect pests, the correct branch is entomology.
Answer:A. entomology