The correct answer is D. Preventive health services. Health benefit plans issued on or after January 1, 2014 became subject to the Affordable Care Act’s essential health benefit and preventive-service requirements for non-grandfathered coverage in the individual and small-group markets. Those rules require coverage for specified preventive services without cost-sharing when provided in accordance with federal guidelines. New York’s post-2014 marketplace coverage materials likewise explain that plans must include the ACA’s required essential health benefits, which include preventive and wellness services.

The other options are not the mandatory general requirement described in this question. Adult eye care and adult dental care are not universally required as core benefits in the same way preventive services are; the ACA’s pediatric services category specifically includes pediatric vision and dental, not broad adult routine vision or dental as mandatory across all such plans. Long-term care services are also not one of the essential health benefits that every post-2014 health benefit plan must provide. Therefore, among the choices given, the service that must be provided is preventive health services