Needs help ASAP please and thank you

Brainliest to who answers! what will always cause a supply curve to shift to the left?

Congress is controlled by the democrats. president yaeger, a republican, takes several actions that are opposed by the democrats in congress. first, the president introduces a new budget that cuts most of the government's social programs and gives tax breaks to the wealthy. next, president yaeger negotiates a trade treaty with a nation accused of human rights abuses. then, the president gives pardons to three republican senators who have been convicted of crimes.

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?