Final answer:
Funding for postretirement health care benefits is not legally required, but contributions are generally tax-deductible, which differs from mandatory social insurance programs like Social Security and Medicare.
Step-by-step explanation:
The correct statement regarding the funding for postretirement health care benefits is that it is not legally required and contributions are generally tax-deductible. This falls under the broader category of retirement insurance and associated planning, which involves various forms of savings and health care benefits. It's important to note the distinction between social insurance programs like Social Security and Medicare, and private retirement savings plans such as 401(k)s and 403(b)s. For the latter, employers and employees can make contributions, which are often tax-deferred, meaning taxes are paid upon withdrawal in retirement rather than when the contributions are made.