D.
A fixed allele is homozygous within a population so D should be the correct answer.
Hope this helps!
Answer:
Antibiotics save lives but any time antibiotics are used, they can cause side effects and lead to antibiotic resistance.
Since the 1940s, antibiotics have greatly reduced illness and death from infectious diseases. However, as we use the drugs, germs develop defense strategies against them. This makes the drugs less effective.
Answer:
Susceptible to same diseases.
Explanation:
I just answered something along these lines.