15-The cost-benefit principle is based on the idea that; a- Action should only be taken if the benefits derived from it are greater than the costs. b- Action can be taken if any benefit exists. c- Action can be taken when cost is equal to benefit. d- Action is possible free from the cost and benefit. 16- Economic Optimization is; a- Avearage cost Avearage revenue b- - The strategic allocation of scarce resources to maximize d desired outcomes.within certain constraints. - The same for every person. d- Optimization is notpossible. 17-If you drink one cup of coffee you can be awaken but 4^th cup of coffee may create heartbeat or anxiety..This statement is an example for; a Average revenue. b- Total Revenue.

15- The correct answer is a- Action should only be taken if the benefits derived from it are greater than the costs. The cost-benefit principle is based on the idea that actions should be taken only if the benefits derived from them are greater than the costs. This principle helps in decision-making by comparing the costs and benefits of different alternatives.<br /><br />16- The correct answer is b- The strategic allocation of scarce resources to maximize desired outcomes within certain constraints. Economic optimization refers to the strategic allocation of scarce resources to maximize desired outcomes within certain constraints. It involves finding the most efficient and effective way to achieve a specific goal while considering the limitations and constraints.<br /><br />17- The correct answer is c- Marginal revenue. The statement about drinking coffee and its effects is an example of marginal revenue. Marginal revenue refers to the additional revenue generated from selling one more unit of a product or service. In this case, the additional cup of coffee may create heartbeat or anxiety, indicating the marginal revenue of the fourth cup of coffee.