All of the following must be covered by state Medicaid programs EXCEPT?

State Medicaid programs are mandated to cover a variety of services to ensure that low-income individuals and families have access to essential healthcare. While some benefits are considered mandatory under federal law, others can be optional, which is where understanding the nuances of the choices comes in.

Children's vaccines, freestanding birth center services, and transportation to medical care are all mandatory services that state Medicaid programs must provide. Children's vaccines are critical for preventing diseases and maintaining public health, thus states receive federal funding to ensure these vaccines are accessible to children enrolled in Medicaid. Freestanding birth centers are important for providing maternity care, and transportation services are necessary to facilitate access to healthcare appointments.

On the other hand, vision benefits fall into the category of optional services for Medicaid. While some states choose to offer vision benefits to their recipients, they are not required to do so by federal law. This variability means that benefits can differ significantly from one state to another. Thus, while some Medicaid programs may include vision coverage, it is not universally mandated across all state programs, making it the correct answer in this context.