PLEASE HELP What is the rule for the sequence with the first four terms below?

-8, 32/5, -128/25, 512/125

A.) f(x)=10(-4/5)^x

B.) f(x)=-8(4/5)^x

C.) f(x)=40(-1/5)^x

D.) f(x)=-8(1/5)^x