When new firms enter a perfectly competitive market, A. existing firms may see their costs rise if more firms compete for limited resources. B. entering firms will earn zero economic profit upon entry into the market. C. prices will rise as existing firms raise prices to keep new firms out of the market. D. economic profits of existing firms will continue to be zero.

Who is not spending wisely? erika goes shopping and saves her receipts. she totals how much she spent and writes it down. mia needs to buy a new pair of shoes because she joined the soccer team. she looks at newspaper ads to find the best price. lauren has been thinking about getting a puppy for a long time. she walks by the pet store at the mall and decides to get a puppy. erin makes a purchase online using a credit card. she knows that she can pay the entire bill when it arrives.