Diagram A have 1 mammal (cow and rat) + 1 insect total diversity=2
Diagram B have 1 mammal (cow and rat) + 1 insect + 1 bird total diversity=3
Diagram C have 1 mammal (cow) + 1 insect+ 1 bird+ 1 reptile (snake) total=4
Diagram D have 1 mammal (cow and goat)+ 1 insect + 1 Amphibian (frog) total=3
It means in all given Diagrams, Diagram C have more species diversity.