Every firm has to bear its fixed costs even when it produces nothing

Suppose the United States discovers a way to produce clean nuclear fuel. The effect of this discovery would be to

A) lead the United States to produce less nuclear fuel. B) force the United States to produce at a point inside its PPF. C) shift the U.S. PPF outward. D) shift the U.S. PPF inward.

In a perfectly competitive market,

A) firms can freely enter and exit. B) firms sell a differentiated product. C) transaction costs are high. D) All of the above.