I think answer on this one should be A too. Since we know that 14^7>20^4, as Will said one should always check if the number is positive.is the reasoning for what question and answer pair?
Q: What is the units digit of the expression 14^720^4?
Options:
(A) 8
(B) 3
(C) 4
(D) 6
(E) 0
A: (A)