Another AP physics C multiple choice question

If v is velocity and t is time, A in:

v=A * e^(-Bt)

A. have dimmensions of L/T
B. have dimmensions of (L^2)/T
C. have dimmensions of L/(T^2)
D. have dimmensions of (L^2)/(T^2)
E. none of the above

Hi, I had help earlier but now am now stuck upon another problem -.-'. Can someone help?

E.

Where in the world did "L" come from?
For that matter, where did "B" come from?