Which of the following is another characteristic of animals possessing a solid nerve cord?

Which of the following animals is known as an invertebrate chordate?

Which of the following is not a subphylum of Chordata?

Given below are two statements: one is labelled as Assertion $(A)$ and the other is labelled as Reason $(R)$.
Assertion $(A):$ All vertebrates are chordates but all chordates are not vertebrates.
Reason $(R):$ The members of subphylum Vertebrata possess a notochord during the embryonic period; the notochord is replaced by a cartilaginous or bony vertebral column in adults.
In the light of the above statements,choose the correct answer from the options given below:

One of the primary characteristics of chordates is:

The notochord in vertebrates is modified into