Which of the following describes a substance that induces an immune response?

A cell that passes thru the thymus and is responsible for cell-mediated immunity.

Suppose goods A and B are complements. An increase in the price of good A 

An increase in the price of shoes will shift the demand curve for shoes to the left.

Consider two people: Dave and Mary. They can each produce two goods: corn and wheat. If Dave produces only corn, he can produce 10 units a day. If Dave produces only wheat, he can produce 5 units a day. If Mary produces only corn, she can produce 6 units a day. If Mary produces only wheat, she can produce 8 units a day. Assume their PPFs are linear. Suppose Dave and Mary decide to trade. The range of prices for corn at which gains from trade exist is

Free markets are the best way to organize economic behavior. 

Consider the following demand and supply schedules: If the price in the market is $100

Consider the following PPF. The opportunity cost of a car is 

Lithium and nitrogen react in a combination reaction to produce lithium nitride: 6Li (s) + N2 (g) → 2Li3N (s)How many moles of lithium are needed to produce 0.45 mol of Li3N when the reaction is carried out in the presence of excess nitrogen?

If 588 grams of FeS2 is allowed to react with 352 grams of O2 according to the following unbalanced equation, how many grams of Fe2O3 are produced? FeS2 + O2 → Fe2O3 + SO2