For a manager, building an effective team requires work, but the payoff is stronger, better-performing work unit-good relationships with others in the company, especially your superiors-employees who will work overtime, often without expecting to be paid for it-employees who will do as you say without questioning you-more responsibilities for you and other managers

a stronger, better-performing work unit.

In the question,

As a manager has to build an effective team and that requires a lot of work, but the payoff is a stronger, better-performing work unit.

Building a high performance team for a manager is very important but the effectivity of the team is dependent on the payoff that they are going to get. If the payoff is good then the team feels motivated to work more and also obey the instructions more effectively. The work group culture or the management team generally reinforces this business cycle.

People are supposed to favor the scheme which promises them a long term good return. Higher incentives for the long term period and reasonable incentives for the short term period can also be implemented.

answer(b) equal; set period;