Tanzania’s location has made it an important

area of power

farming community

center of trade

manufacturing community

Farming Community

Explanation:

They liked to farm there.

b) to encourage free trade

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.