**Core Concept**
The correlation between Infant Mortality Rate (IMR) and Socio-Economic status is a well-established public health principle. IMR serves as a sensitive indicator of the overall health and well-being of a population, with lower IMR rates reflecting better socio-economic conditions, healthcare access, and living standards.

**Why the Correct Answer is Right**
A strong negative correlation exists between IMR and Socio-Economic status. This is because lower socio-economic status is associated with higher rates of poverty, poor living conditions, inadequate access to healthcare, and limited education, all of which contribute to increased infant mortality rates. Studies have consistently shown that countries with higher socio-economic development tend to have lower IMR rates. This correlation is influenced by various factors, including maternal healthcare, prenatal care, immunization rates, and access to clean water and sanitation.

**Why Each Wrong Option is Incorrect**
**Option A:** This option suggests a positive correlation, which is incorrect because lower socio-economic status is associated with higher IMR rates, not lower.

**Option B:** This option underestimates the strength of the correlation between IMR and Socio-Economic status. While a correlation of +0.5 may be observed in some contexts, it does not accurately reflect the strong negative relationship between these two variables.

**Clinical Pearl / High-Yield Fact**
It's essential to remember that IMR is a critical indicator of a country's overall health status and socio-economic development. A strong correlation between IMR and Socio-Economic status highlights the importance of addressing poverty, improving access to healthcare, and promoting education to reduce infant mortality rates.

**Correct Answer:**
✓ Correct Answer: D. Correlation (– 0.8)