What events lead to 16th amendment?

Why did buffalo herds decline in the 1830s and 1840s? a. increased numbers of native american buffalo hunters b. increased demand on buffalo meat in eastern restaurants c. increased demand on water resources on the plains d. increased market for buffalo robes

This refers to weather and atmospheric conditions measured over a long period of time.

Martha participates in a research study in order to receive extra credit for her psychology class. when she arrives in the research office she is given a can of what looks and tastes like beer, but which actually contains no alcohol. in the adjoining room martha's classmate karen is also participating in the study. karen receives a can of alcoholic beer. if the experiment was designed to test the effects of alcohol on concentration, then who is exposed to the independent variable?