Compare sickle cell disease and malaria. compare sickle cell disease and malaria. sickle cell disease and malaria are both genetic diseases. sickle cell disease and malaria are both infectious diseases. sickle cell disease and malaria are both inherited diseases. sickle cell disease and malaria are both potentially lethal diseases.

The correct answer is the final option - sickle cell disease and malaria are both potentially lethal diseases. 
The other options are incorrect because sickle cell disease is an inherited disease, but malaria is not - it is an infectious disease. However, both of these disease are quite dangerous, and may have severe consequences (such as death) if they are not properly treated.

Spherical shaped cell might increase the surface area and decrease the volume.