A sample is tested for its phage content performing an assay similar to what we did in class. A one milliliter sample of the sample is diluted in a 1:10 dilution series. One milliliter of the fourth dilution tube is mixed with the appropriate bacteria in soft agar and poured into a petri dish already containing a layer of agar. After incubation, the plate has 32 plaques, indicating that the original sample contained _______. a. 3,200 phage per milliliter. b. 320,000 phage per milliliter c. 3,200,000 phage per milliliter d. 32,000 phage per milliliter