Assertion (A): All vertebrates are chordates but all the chordates are not vertebrates.
Reason (R): All the vertebrates are characterised by the presence of a notochord, a dorsal hollow nerve cord and paired pharyngeal gill slits at some stages of the life cycle.
1. Both (A) and (R) are true and (R) is the correct explanation of (A).
2. Both (A) and (R) are true but (R) is not the correct explanation of (A).
3. (A) is true but (R) is false.
4. Both (A) and (R) are false.