How does being heterozygous for the sickle cell trait provide resistance to malaria?

• A. Heterozygous individuals have some sickle-shaped cells that resist malaria infection.
• B. Heterozygous individuals have all sickle-shaped cells and are fully resistant to malaria.
• C. Heterozygous individuals have no sickle-shaped cells and are fully susceptible to malaria.
• D. Heterozygous individuals have normal cells that resist malaria infection.

Answer: (A)