Answer:
The correct answer is a. Due to natural genetic variation within the population,resistant bacteria will be present even in the absence of antibiotic.
Step-by-step explanation:
It is very important to state that Antibiotic resistance in a bacteria cannot be developed in the absence of that antibiotic.
If this really happen(generation of antibiotic resistance even in the absence of a particular antibiotic) then no antibiotics can be effective in the treatment of bacterial diseases.