**Core Concept:**

The question is testing the term used to describe the change in an individual's socioeconomic status, specifically whether an individual moves from a lower socioeconomic stratum to a higher one or vice versa. This includes concepts related to social mobility and its effects on health outcomes.

**Why the Correct Answer is Right:**

The correct answer, **C. Social Mobility**, refers to a person's ability to change their social class position over time. This concept encompasses both upward social mobility, where an individual moves from a lower socioeconomic status to a higher one, and downward social mobility, where an individual moves from a higher socioeconomic status to a lower one. Understanding social mobility is crucial for healthcare professionals, as it impacts an individual's health outcomes and access to healthcare resources.

**Why Each Wrong Option is Incorrect:**

A. **Social Stratification (A):** This term is related to the classification of social groups based on socioeconomic status, but it does not address the movement between these groups over time, making it incorrect.
B. **Social Mobility (B):** Although this term is related to changes in social class, it specifically refers to a change in position within the same socioeconomic stratum, not the change between strata.
D. **Social Class (D):** This term refers to a person's position within a specific socioeconomic stratum but does not address the concept of change between strata over time.

**Clinical Pearl / High-Yield Fact:**

Understanding social mobility is essential for practicing physicians because it can influence an individual's health behaviors, access to healthcare resources, and overall health outcomes. By considering a patient's social mobility, healthcare providers can provide more personalized care, address social determinants of health, and promote health equity.