In the new world build the relationship between east and west africa. a. a shared water supply c. arranged marriages b. advanced transportation systems d. trade

d. Trade is the answer. East and West Africa learned more about each other through trading. Sharing water supply would cause conflict, arranged marriages would require a bond beforehand to marry one of your people to another's people. Advanced transportation systems would still not create a relationship. Trade is the logical answer, and I had this question, I said d, and it was right.

this null effect is caused by a weak manipulation and ineffective internal validity. in a scientific study, as the one dr. morimoto is trying to perfom, internal validity refers to the confidence placed in the cause-effect relationship and to how well an experiment is done and able to eliminate confounding variables.