All chordates possess $..........$.

The most important distinctive character of $Chordata$ is the presence of

The common characteristic of all vertebrates without exception is:

What type of feeding mechanism is observed in Cephalochordates?

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:

Which of the following is a group of invertebrate chordates?