50. A magnetic flux is through the conducting loop according to the relation ΦB(t) = 6t2 + 7t, whereΦB is in milliwebers and t is in seconds. What is the magnitude of the emf induced in the loop when t=2.0 s?
(A) 38mV
(B) 30 mV
(C) 31 mV
(D) 15 mV
(E) 15.5 mV