**Core Concept**
Primary health care (PHC) is a holistic approach to healthcare that emphasizes community involvement, accessibility, and acceptability of health services. It focuses on preventing and treating diseases at the primary level, addressing social determinants of health, and promoting health equity. PHC is a key component of the World Health Organization's (WHO) vision for achieving universal health coverage.

**Why the Correct Answer is Right**
The correct answer, Primary Health Care (A), is the correct definition because it aligns with the WHO's Alma-Ata Declaration (1978), which aimed to make health care universally accessible and acceptable to individuals worldwide. PHC emphasizes the importance of community participation, intersectoral collaboration, and social and economic development in achieving health equity. This approach recognizes that health is a fundamental human right and that individuals should have access to essential health services, including preventive, curative, and rehabilitative care.

**Why Each Wrong Option is Incorrect**
**Option B:** Essential health care is not a widely recognized term in the context of universal health coverage. While essential health services are a crucial component of PHC, the term "essential health care" does not fully capture the scope and philosophy of PHC.

**Option C:** Community health care is a broader term that encompasses various approaches to healthcare, including PHC. However, it does not specifically convey the emphasis on universal accessibility and acceptability that PHC embodies.

**Option D:** Social Medicine is a field of study that examines the social determinants of health and the impact of social factors on health outcomes. While it is related to PHC, it is not a synonym for PHC and does not capture the full scope of PHC's focus on universal health coverage.

**Clinical Pearl / High-Yield Fact**
A key principle of PHC is that health is a fundamental human right, and individuals should have access to essential health services, regardless of their socioeconomic status or geographical location. This principle is enshrined in the WHO's Constitution and is a cornerstone of international efforts to achieve universal health coverage.

**✓ Correct Answer: A. Primary health care**