How many bacteria were there in the initial 1 ml sample based on the dilution series shown below? The labels below the tube show the amount of liquid before the transfer. Assume no cell death, and assume that all bacteria successfully form colonies when plated.
a. 6.5 x 108
b. 6.5 x 109
c. 6.5 x 1010
d. 6.5 x 1011
