How long had you owned/been owning the flat before you sold it?Which is the correct answer?

the economic activity signified in that scenario is a. production

in general, market production makes reference to the elaboration of a product or service which is destinated for economic purposes (to be sold) at money-price in a market. such product or service has to be principally tradable for money.

there is no money exchange involved in distribution, generalized reciprocity or balanced reciprocity.

(4) "oh, i've got better plans than that," laughed kerry. "i've got four firecrackers and two model rockets. care to join me in the backyard? "

this is the correct answer because of one simple word. "backyard"