Answer:
C
Step-by-step explanation:
The correct answer would be plant pathology.
The branch of biology that is generally concerned with the study of diseases is referred to as pathology. When such a study has to do with plants, it is known as plant pathology.
Mycology is the branch of biology that has to do with the study of fungi, phycology deals with the study of algae, while agronomy deals with the study of economically important crops.
Hence, the correct option is C.