<prompt> Which of the following is true about sickle cell red blood cells?StabilityAltered functionDecreased oxygen carrying capacityProtective against adult malaria  <response>: HbAS heterozygotes sickle cell trait have a sixfold reduction in the risk of dying from severe falciparum malaria. This decrease in risk appears to be related to impaired parasite growth at low oxygen tensions and reduced parasitized red cell cytoadherence. Parasite multiplication in HbAE heterozygotes is reduced at high parasite densities. Ref: White N.J., Breman J.G., Osler W. 2012. Chapter 210. Malaria. In D.L. Longo, A.S. Fauci, D.L. Kasper, S.L. Hauser, J.L. Jameson, J. Loscalzo Eds, Harrisons Principles of Internal Medicine, 18e. 