Describe sickle cell anemia as an example of balanced polymorphism and mention a pleiotropic effect.

• A. Heterozygotes have malaria resistance; homozygotes have disease.
• B. Heterozygotes gain malaria resistance; homozygotes have disease; HbS also affects red blood cell shape and can cause vascular issues.
• C. Homozygotes have malaria resistance.
• D. HbS only affects red blood cell shape but does not influence disease or malaria.

Answer: (B)