How does heterozygote advantage maintain genetic variation in a population, using the sickle cell trait as an example?

• A. It eliminates individuals with two recessive alleles.
• B. It ensures all individuals have at least one sickle cell allele.
• C. It provides resistance to malaria without causing full sickle cell disease symptoms.
• D. It causes rapid fixation of one beneficial allele.

Answer: (C)