A bacterium in a petri dish multiplies by a factor of 2 every day. On day O, there is 1 bacterium; on day 1, there are 2 bacteria, on day 2, there are 2•2 = 4 bacteria; on day 3, there are 2•2•2=8 bacteria, and so on. What logarithmic equation can be used to find the number of days it takes for a colony of 1,000,000,000 bacteria to develop?

A: 1,000,000,000x = log10 2

B: 1,000,000,000 = log2 x

C: x= log2 1,000,000,000

D: x^2 = log10 1,000,000,000