Answer:
The bacteria with sensitive allele will have the highest fitness in the absence of antibiotic, and the antibiotic-resistant allele will have the highest fitness cost in the presence of antibiotic.
Step-by-step explanation:
Antibiotic resistance can impair bacterial growth or competitive ability in the absence of antibiotics, frequently referred to as a ‘cost’ of resistance. Theory and experiments emphasize the importance of such effects for the distribution of resistance in pathogenic populations. So as such bacteria with sensitive allele will have the highest fitness in the absence of antibiotic, and the antibiotic-resistant allele will have the highest fitness cost in the presence of antibiotic.