Assertion : Nerve cells in coelenterata have complete co-ordination in their body.
Reason : True nerve cells occur for the first time in coelenate.

Options

A. If both the assertion and the reason are true and the reason is a correct explanation of the assertion
B. If both the assertion and reason are true but the reason is not a correct explanation of the assertion
C. If the assertion is true but the reason is false
D. If both the assertion and reason are false

Answer

A

Explanation

Coelenterates possess a very primitive type of nervous system. This system is composed of many nerve cells. In coelenterates, the separate mechanisms for digestion, respiration and excretion, repoduction ect evolved for the first time. Thus there is a constant need to maintain corrdination between these systems. Nerve cells are develope for this purpose, for the first time in coelenterates. Nerve in Hydra is the beginning in the evolution for nervous system.