Not one American soldier bound for Europe was lost to submarine attacks because of a. alliances.
C. convoys.
b. airplanes
d. entente.

food chain i would say only because there is competition on getting food and survival

biological/genetic factors means they were born or predisposed to have something. nothing can really change it, and you can't really do much to "fix" it. it isn't something learned

these are the biological factors:

adrian is relatively tall and he is on the basketball team

(adrian can't ever stop being tall or force himself to be tall. likely one or both of his parents are tall as well and they passed on the tall gene. he probably does basketball because he is tall)

the rest are environmental/cultural factors. these are things that are taught to us. for example, cynthia wasn't born saving pocket money, her family most likely taught her this (environmental factor)

hope this !

c. the passage of the fifteenth amendment