**Core Concept**
The question is testing the association between socioeconomic status (SES) and physical activity or movement levels. SES is a complex construct that encompasses various factors, including income, education, occupation, and access to resources. Research has consistently shown that individuals from lower SES backgrounds tend to engage in less physical activity and have poorer health outcomes compared to those from higher SES backgrounds.

**Why the Correct Answer is Right**
The relationship between SES and physical activity is multifaceted. Individuals from lower SES backgrounds often face barriers to physical activity, such as limited access to safe and affordable recreational spaces, lack of transportation, and increased exposure to environmental hazards. Furthermore, the demands of work and family responsibilities can leave individuals with limited time and energy for physical activity. This can lead to a vicious cycle of sedentary behavior, poor health, and further socioeconomic disadvantage.

**Why Each Wrong Option is Incorrect**
* **Option A:** While education level can influence physical activity, it is not the sole determinant of SES. Individuals from lower SES backgrounds may have limited access to education and resources, making it difficult to engage in physical activity.
* **Option B:** Occupation is a component of SES, but it does not directly explain the relationship between SES and physical activity. Some occupations may require physical activity, while others may be sedentary.
* **Option C:** Access to healthcare is an important aspect of SES, but it does not directly influence physical activity levels. Individuals from lower SES backgrounds may have limited access to healthcare, but this does not necessarily mean they are less active.

**Clinical Pearl / High-Yield Fact**
The "social determinants of health" framework highlights the importance of socioeconomic factors in shaping health outcomes. This includes access to education, employment, housing, and healthcare, all of which can influence physical activity levels and overall health.

**Correct Answer:** D.