**Core Concept**
The question is testing the concept of **standardization** in epidemiology, specifically the comparison of mortality rates between two populations. Standardization is a statistical method used to adjust for differences in population characteristics, such as age and sex, to make comparisons more meaningful.

**Why the Correct Answer is Right**
The correct answer is the **Age-Standardized Mortality Rate (ASMR)**. ASMR is a measure of mortality that adjusts for the differences in age distribution between two populations. This is done by applying the age-specific mortality rates of one population to the age distribution of another population. This allows for a more accurate comparison of mortality rates between the two populations.

**Why Each Wrong Option is Incorrect**
**Option A:** is incorrect because **Crude Death Rate (CDR)** does not account for differences in population characteristics, such as age and sex. CDR is a simple ratio of deaths to population size, without any adjustment for age or other factors.
**Option B:** is incorrect because **Mortality Rate Ratio (MRR)** is a measure of the relative difference in mortality rates between two populations, but it does not account for differences in population characteristics.
**Option C:** is incorrect because **Life Expectancy (LE)** is a measure of the average number of years a person is expected to live, but it does not provide a direct comparison of mortality rates between two populations.

**Clinical Pearl / High-Yield Fact**
When comparing mortality rates between two populations, it's essential to standardize for age and other population characteristics to avoid biases and ensure accurate conclusions.

**Correct Answer: C. Mortality Rate Ratio (MRR) is not the correct answer, the correct answer is Age-Standardized Mortality Rate (ASMR) is not listed, but the closest option is B. Standardized Mortality Ratio (SMR) is a more accurate answer.**