Aproducer charges $500 for a cell phone, but buyers are not buying any cell phones at this price. so at this price, the producer is willing to supply phones, and consumers are willing to buy phones.

by using  production possibilities graph.  opportunity costs are key expenses in financial matters and are utilized as a part of registering money saving advantage investigation of a venture. such expenses, be that as it may, are not recorded in the record books but rather are perceived in basic leadership by processing the money costs and their subsequent benefit or misfortune.

the answer your looking for is c. : )