Answer
HBA HBs
Explanation:
In some parts of Africa, up to 20% of the population are carriers of the sickle cell gene. This suggests that the trait must have a survival value. The carriers of the trait have a much lower susceptibility to malaria than normal individuals. This is because the malaria parasite survives very poorly in sickled red blood cells.
The Vascular system transports water and sugars throughout the plant during photosynthesis.
