Final answer:
Option (a), The retirement benefit plan where costs equal contributions is the defined contribution plan. These tax-deferred, portable plans, like 401(k)s, allow investment flexibility and can protect retirees against inflation.
Step-by-step explanation:
The type of post-employment benefit plan where the retirement benefit cost is equal to the contribution due for the period is known as a defined contribution plan. In a defined contribution plan, such as 401(k)s and 403(b)s, the employer contributes a fixed amount to the employee's retirement account on a regular basis. The contributions are typically tax deferred and the plans are portable, meaning they can be transferred if the employee changes jobs.
These plans allow for investment in a wide range of vehicles, and to the extent that the investments made generate real rates of return, retirees are better protected against inflation compared to traditional defined benefit pensioners.
Pension insurance is also relevant to retirees, as it offers a level of protection. Employers that offer pensions are required to pay a fraction of what they are setting aside for pensions to the Pension Benefit Guarantee Corporation, ensuring that workers receive at least some benefits even if a company cannot fulfill its pension promises due to bankruptcy.