Consider a Culture of 1,000 Cells

Consider a culture of 1,000 cells. Each cell divides once to yield a total of 2,000 cells. A measurement of the mutation rate in this culture would be based on the total number of

A) 2,000 cells.
B) genes in the bacterium.
C) generations, which in this case is one.
D) cell divisions, which is 1,000.
E) mutations found in that culture.