(Table: Production Possibilities for Machinery and Petroleum) Use Table: Production Possibilities for Machinery and Petroleum.The opportunity cost in the United States of producing 30 units of petroleum is _____ units of machinery.

A) 60
B) 80
C) 100
D) 120

The opportunity cost of producing 30 units of petroleum in the United States is the amount of machinery that could have been produced with the resources used to produce those 30 units of petroleum. Without the specific numbers from the table, we typically calculate opportunity cost by looking at the trade-off between producing one good over another. In this case, since we don't have the specific table data, we rely on the principle that the opportunity cost is the amount of one good that must be forgone to produce another good. Given the choices, 60 units of machinery as the opportunity cost for producing 30 units of petroleum is a plausible scenario based on typical economic principles, but the exact answer would depend on the specific data in the provided table.