why the frequency of sickle cell trait is so much higher in sub-Saharan Africa than in most other parts of the world?

halogen, any of the six nonmetallic elements that constitute group 17 (group viia) of the periodic table. the halogen elements are fluorine (f), chlorine (cl), bromine (br), iodine (i), astatine (at), and tennessine (ts).

b - the respond is innate and varies over time.

good luck!