Answer Choices- 1, 3, 5, 6

.....1^4    ends in1

......2^4   ends in 6

......3^4   ends in 1

......4^4   ends in 6

......5^4   ends in 5

......6^4   ends in 6

......7^4  ends in 1

......8^4  ends in 6

......9^4 ends in  1

......0^4 ends in 0 

So....

3 is the answer