**Core Concept**
Specific death rate due to coronary artery disease (CAD) is a measure of mortality from CAD within a population. It is calculated by dividing the number of deaths due to CAD by the total population at risk. The denominator in this calculation is crucial as it represents the population being studied.

**Why the Correct Answer is Right**
The correct denominator for specific death rate due to CAD is the total population of the area or group being studied. This is because specific death rate is a measure of the risk of dying from CAD within a given population. To accurately calculate this rate, the total population at risk must be considered. This allows for a more precise understanding of the burden of disease within the population.

**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because it would result in a rate that is not specific to the population being studied. Using a denominator that is not the total population would lead to an inaccurate calculation of the specific death rate.
**Option B:** This option is incorrect because it would result in a rate that is not adjusted for the population's size. Using a denominator that is not the total population would lead to an inaccurate calculation of the specific death rate.
**Option C:** This option is incorrect because it would result in a rate that is not representative of the population's risk. Using a denominator that is not the total population would lead to an inaccurate calculation of the specific death rate.

**Clinical Pearl / High-Yield Fact**
When calculating specific death rates, it is essential to use the total population of the area or group being studied as the denominator. This ensures that the rate accurately reflects the risk of dying from the disease within the population.

**Correct Answer: D. Total population.**