2. Claisen rearrangement of allyl phenyl ether to ο-allylphenol is a sigmatropic rearrangement. Thisrearrangement is a [x, y] shift and proceeds under what condition.
(A)[1，3] ; thermal
(B) [1,3] ; hν
(C) [1,7] ; hν
(D) [3,3] ; thermal
(E) [3, 5] ; hν