Which equation represents a geometric sequence?

A. y=2x+3

B. y=x^2+5x-6

C. y=x^3-1

D. y=4^x+3

I think the answer is A, but I could be wrong. I think the answer is A, because it is the only equation that is linear. In mathematics a geometric sequence is a sequence of numbers where each term after the first is found by multiplying the previous one by a fixed, non-zero number, meaning when you graph it the line should be linear. Of all of these A is the only that is Linear the others are not. The slope of line A is 2 and the Y-intercept is 3.