Find the odd word pair out from the given options.

The logic followed here is: In all the pairs, the 1st word represents the name of study and the 2nd word represents the field of study for the first word. Cytology : Cell = The study of cell is called cytology. Agrostology : Grass = The study of grasses is called agrostology. Entomology : Fishes = Entomology is the study of insects. The study of fishes is called Ichthyology. Hematology : Blood  = The study of blood is called Hematology.   Thus, ‘Entomology : Fishes’ is the odd one out. Hence, the correct answer is (C).