In which of the following is the notochord present during the embryonic stage?

What type of feeding mechanism is observed in Cephalochordates?

The body of a urochordate is enclosed in a

Urochordata: All the members of this subphylum are:

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:

Provide definitions/explanations for the following terms:
$(i)$ Cephalochordata
$(ii)$ Pseudocoelomates