Final answer:
The minimum volume that 500 mg of erythromycin can be in at a maximum concentration of 5 mg/ml is calculated to be 100 ml.
Step-by-step explanation:
To find out the minimum volume that 500 mg of erythromycin can be in, given a maximum concentration of 5 mg/ml, we use the following calculation:
Volume = Amount of drug (mg) / Concentration (mg/ml)
So,
Volume (ml) = 500 mg / 5 mg/ml
Volume (ml) = 100 ml
Therefore, the minimum volume of erythromycin at this concentration would be 100 ml, which corresponds to option b).