A cost is O something that is gained when a decision is made
O something that is given up when a decision is made
Oa rational decision
Oa type of benefit

something that is given up when a decision is made

Explanation:

if something costs you it goes away

for example if the cost of some was 2 dollars you would lose two dollars

john maynard keynes developed new economic theories in response to the stock market crash of 1929. great depression of the 1930s. first and second world wars. economic boom of the 1950s.

a, both were musicians during the jazz age