A sample of raw, unpasteurized milk is tested for its bacterial content in a plate count assay. A one-milliliter sample of the milk is diluted in a 1:10 dilution series. One milliliter of the third dilution tube is plated in a pour plate. After incubation, the plate has approximately 500 colonies, indicating that the original milk sample contained:

A) 500,000 bacteria/ml
B) 50,000 bacteria/ml
C) 5,000 bacteria/ml
D) 500 bacteria/ml
E) 50 bacteria/ml