Questions

The question involves evaluating both the Assertion (A) and the Reason (R) and choosing the most appropriate answer from the options provided. Let's analyze them:

Assertion (A): Four distinctive characteristics of phylum Chordata are notochord; single, dorsal, tubular nerve cord; pharyngeal pouches and postanal tail.

Reason (R): The distinctive characteristics of phylum Chordata remain unchanged throughout the life of these animals.

1. Analyzing Assertion (A): This is a true statement. The four characteristics mentioned are indeed the distinctive features of phylum Chordata.

2. Analyzing Reason (R): This statement is incorrect. The distinctive characteristics mentioned might not always remain unchanged throughout the life of these animals. For example, in some chordates, the notochord is replaced by a vertebral column during development (such as in vertebrates).

Given this evaluation:

• (A) is correct.
• (R) is not correct.

Therefore, the correct answer is:

Option 3: (A) is correct but (R) is not correct.