A sample of 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 54 colonies, indicating that the original milk sample contained:
a. 54 cells.
b. 540 cells.
c. 5400 cells.
d. 54,000 cells.
e. 540,000 cells.