Which number is the smallest?

Responses
A 1.28 x
1.28 x 10 -^4
B 2.85 x 10-^6
2.85 x 10 -^6
C 3.24 x 10-^5
3.24 x 10 -^5
D 4.68 x
4.68 x 10^ -4
E 5.48 x 10-^8

E 5.48 x 10^-8