The level of an economic activity should be increased to the point where the ____ is zero

Which of the following is an example of the "metering" strategy

a. A doll company selling dolls at cost but charging high margins on doll accessories b. A cell phone company offers free locked in phones but charges high prices per call c. A catering company pays its chefs higher wages to make sure that the bargain meals are just slightly burnt d. Only A&B

Pigou buys a house for $500,000, rents it for $2,000 per month for four years, and then sells it for $600,000. What is Pigou's per-year rate of return?

A. 4.8 percent. B. 9.8 percent. C. 20 percent. D. 39.2 percent.