The Blood Agar Plate of a Urine Specimen Shows 100

The blood agar plate of a urine specimen shows 100 colonies of a large gray wet beta-hemolytic organism. The MacConkey agar displays 20 colonies of a dark pink lactose fermenter. Both organisms are E. coli. How do you account for the difference in the number of colonies between the two agar plates?

A) E. coli grows much better on sheep blood agar than on MacConkey agar.
B) There is a dilution effect as the agar is struck so there will be fewer colonies from agar to agar.
C) The technologist did not redip the loop into the urine before inoculation of the MacConkey.
D) The technologist did not flame the calibrated loop after inoculation of the blood agar plate.