Health care disparities are best defined as:

Health care disparities refer to the differences in health outcomes and access to healthcare services that are closely linked with social, economic, and environmental disadvantages. This definition encompasses how various factors, such as income, education, race, and location, can result in unequal access to medical care and ultimately affect an individual's health status.

Choosing the option related to social, economic, and environmental factors highlights the broader context that contributes to these disparities, including systemic issues that can create barriers to achieving optimal health outcomes. It draws attention to the importance of addressing these underlying factors to effectively reduce disparities in health care access and quality.

Other options may touch upon aspects of healthcare delivery, such as differences in service access or hospital availability, but they do not capture the multifaceted nature of disparities as effectively. They tend to focus on isolated elements rather than the comprehensive, interrelated factors that contribute to health inequities. Recognizing the role of social determinants of health provides a more complete understanding of why certain populations experience worse health outcomes and is crucial for developing strategies to improve health equity.