A = Phylum chordata is divided in to three subphylum.
R = They have urochordata, cephalochordata and vertebrata
(A) Both Assertion and Reason are true and Reson is the correct explanation of Assertion.
(B) Both Assertion and Reason are true but Reason is not the correct explanation of Assertion.
(C) Assertion is true but reason is false
(D) Both Assertion and Reason are false.
(E) Assertion is false but reason is true.