Arrange in increasing order of number of species to represent global biodiversity?

(A) Molluscs
(B) Crustaceans
(C) Insects
(D) Other animal groups

Choose the correct answer from the options given below:

(B), (A), (D), (C)

The correct answer is Option (3) → (B), (A), (D), (C)   

(B) Crustaceans have relatively lower species richness among the groups listed.

(A) Molluscs have higher species richness than crustaceans but are still lower compared to other animal groups.

(D) Other animal groups (such as annelids, nematodes, and arachnids) have moderate species richness.

(C) Insects have the highest species richness among invertebrates by far, with millions of described species.