Which among these is a vertebrate A. Cockroach B. Earthworm C. Hen D. Sponge

The correct answer is C. Hen.
A vertebrate is an animal that possesses a vertebral column (spine or backbone), which is a defining characteristic of the subphylum Vertebrata within the phylum Chordata. Vertebrates include animals such as mammals, birds, reptiles, amphibians, and fish.
Let's examine each option in detail:
1. A. Cockroach: A cockroach is an invertebrate (lacks a backbone) and belongs to the class Insecta in the phylum Arthropoda. Therefore, it is not a vertebrate.
2. B. Earthworm: An earthworm is also an invertebrate. It belongs to the phylum Annelida and lacks a vertebral column.
3. C. Hen: A hen is a vertebrate because it is a bird, and birds belong to the class Aves in the subphylum Vertebrata. Birds have a backbone, making them vertebrates.
4. D. Sponge: Sponges are invertebrates and belong to the phylum Porifera. They do not have a backbone or any form of nervous system, so they are not vertebrates.
The only vertebrate among the options is the hen (C), as it has a backbone, which is the characteristic feature of vertebrates. Therefore, the correct answer is C. Hen.