Which benefit is directly related to TRICARE's pharmacy program?

The benefit that is directly related to TRICARE's pharmacy program is access to prescription medication. TRICARE offers a comprehensive pharmacy program designed to provide eligible beneficiaries with access to necessary medications at low costs. This program includes both brand-name and generic medications available through military pharmacies, retail pharmacies, and a home delivery option.

While the other options mention important aspects of healthcare, they do not relate to the pharmacy program. Vision care services, lab tests, and annual physical exams are all separate healthcare services that fall under different categories of TRICARE benefits, but they do not specifically pertain to the distribution or management of prescription medications. Access to prescription medication is central to TRICARE's efforts to ensure that beneficiaries receive necessary pharmaceutical care.