**Core Concept**
The concept being tested is a statistical method used to compare the mortality rates of two distinct populations. This involves calculating a ratio of observed deaths to expected deaths, which helps in assessing the relative risk of death between the two groups.

**Why the Correct Answer is Right**
The correct answer is the **Standardized Mortality Ratio (SMR)**. SMR is a statistical measure used to compare the death rates of two populations by standardizing the rates to a common population. This is achieved by calculating the ratio of observed deaths to the expected number of deaths in the standard population. For example, if the observed deaths are 100 and the expected deaths are 80 in a standard population, the SMR would be 100/80 = 1.25, indicating a 25% higher death rate in the study population compared to the standard population.

**Why Each Wrong Option is Incorrect**
**Option A:** The **Mortality Rate** is a measure of the number of deaths per unit population over a specified time period, but it does not account for the size or characteristics of the population.
**Option B:** The **Case Fatality Rate** is a measure of the proportion of individuals with a specific disease who die from that disease, but it does not compare the death rates between two populations.
**Option C:** The **Relative Risk** is a measure of the ratio of the probability of an event occurring in the exposed group versus the non-exposed group, but it is not specifically used to compare death rates between two populations.

**Clinical Pearl / High-Yield Fact**
When comparing mortality rates between two populations, it is essential to consider the standardization of rates to account for differences in population demographics and characteristics.

**Correct Answer:** C.