All vertebrates are chordates but all chordates are not vertebrates, why?

Role of the water vascular system in Echinoderms is : A. Respiration and Locomotion B. Excretion and Locomotion C. Capture and transport of food D. Digestion and Respiration E. Digestion and Excretion Choose the correct answer from the options given below :

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 vertebrate. Reason (R) : The members of subphylum vertebrata possess notochord during the embryonic period, the notochord is replaced by cartilaginous or bony vertebral column in adults. In the light of the above statements, choose the correct answer from the options given below:

All living members of the class Cyclostomata are :

While trying to find out the characteristic of a newly found animal, a researcher did the histology of adult animal and observed a cavity with presence of mesodermal tissue towards the body wall but no mesodermal tissue was observed towards the alimentary canal. What could be the possible coelome of that animal?

Match List-I with List-II. \begin{array}{|l|l|l|l|}\hline & List-I & & List-II \\\hline A. & Chondrichthyes & I. & Clarias \\\hline B. & Cyclostomata & II. & Carcharodon \\\hline C. & Osteichthyes & III. & Myxine \\\hline D. & Amphibia & IV. & Ichthyophis \\\hline\end{array} Choose the correct answer from the options given below: