Answer 3. ( B ) i.e 1.  

Reason : According to cost benefit principle a person should take an action if and only if the extra benefits from taking the action it is greater than the extra cost. So here when 0 ride is taken total cost is 0 an total benefit is also 0. when taken 1 ride the total cost is 10 and total benefit is 12. So the benefit form 1 ride is greater than 0. That is 12>10. If 2 rides is taken then then extra cost is 10 and extra benefit is 8 so here extra benefit is smaller than the extra cost so we should not take 2 ride and so on if 3 ride is taken extra benefit is 5 and extra cost is 10 so will not take 3 ride and so on..

Answer 4. ( B). i.e efficient point.

Reason : in economics term efficient point is a point at which a consumer will produce effectively within the given time , technology, and resources so here when production of fish is not increased at that time chunk is producing inefficiently. Now if he increase his productions without decreasing the selling of printers then he is producing efficient or at efficient point. Ideal point is a point which lies outside the the economy which here is not possible.