which of the following choices is the explicit formula for the following geometric sequence?

-0.1, 0.02, -0.004, 0.0008, -0.00016

A. an = 0.1(0.2)n
B. an = 0.1(-0.2)n-1
C. an = -0.1(-0.2)n-1
D. an = 0.2(-0.2)n-1
E. an = -0.1(0.2)n-1