Decision variables:

A. tell how much or how many of something to produce, invest, purchase, hire, etc.
B. represent the values of the constraints.
C. measure the objective function.
D. must exist for each constraint.

The correct answer is A. tell how much or how many of something to produce, invest, purchase, hire, etc.

Explanation:

With the decision variables we represent the questions that we have and that motivate the formulation of the optimization problem. These questions must have a numerical answer, which implies a specific action and this action must be under our control.

there was no passage listed but using the process of elimination i'd say it was d. the high economy would do the opposite. i don't see how low prices would affect it. high unemployment is possible but i feel d is the better answer.

answer; sensory adaptation;