Carroll’s diner decides to hire a new waitress to out with waiting tables. the new waitress costs the diner $1700 per month. the ability for customers to be served more quickly allows the diner to make an extra $2500 than previously. how do we know that carroll's diner made a rational economic decision? voluntary exchange led to the waitress making $1700 a month. the marginal benefit of $2500 is greater than the marginal cost of $1700 for the new waitress. specialization led to the diner making $2500. none of these; scarcity of resources does not allow for rational decisions to ever be made.

The marginal benefit of $2500 is greater than the marginal cost of $1700 for the new waitress.

In economics, a rational decision is a decision where the total benefit equals or exceeds the costs associated with that decision.  

In this case, Carroll's diner pays the new waitress $1700, but is able to earn  $2500 by serving customers more quickly.  Since the diner earns $800 (2500 -1700) more than the cost paid to the waitress, we can say that hiring an additional waitress is a rational economic decision.

answer; i believe that the correct answer is (d); the business benefits because owners can share responsibilities;