Why Would Antimicrobials That Have Toxic Side Effects Be Used

Why would antimicrobials that have toxic side effects be used at all (select the BEST reason) ?

A) We want the largest possible number of choices of drugs in case a microbe shows resistance.With more possible weapons (even toxic ones) ,we have greater ability to eliminate infections.
B) Every person is different.What is toxic to one person may not be toxic to another person.To eliminate a useful drug because it's toxic to 1% of people treated is a waste.
C) Depending on the location of the infection,we may have no choice but to utilize a drug that has some toxic side effects to the patient.
D) They shouldn't be used.We have enough of a selection of drugs that we can always select a drug with no toxicity.Drugs with toxicity are simply leftovers-relics from a time when we didn't have as many drug options.