## Core Concept
The **death rate**, also known as mortality rate, is a measure of the number of deaths in a population over a specific period of time, usually expressed per 1000 people per year. It is an important epidemiological measure used to assess the health status of a population. In this scenario, we need to calculate the death rate based on the given data about cholera cases and total deaths.

## Why the Correct Answer is Right
To calculate the **death rate**, we use the formula: (Total number of deaths / Total population) * 1000. Given that there are 50 total deaths and a population of 5000, we can substitute these values into the formula: (50 / 5000) * 1000 = 10. This means the death rate is 10 per 1000 population.

## Why Each Wrong Option is Incorrect
- **Option A:** This option is incorrect because it does not accurately reflect the calculation for death rate; it seems to confuse the death rate with the case fatality rate of cholera.
- **Option B:** This option seems to represent a **case fatality rate** (10 deaths out of 50 cholera cases, which equals 20%) rather than a death rate for the entire population.
- **Option C:** This option might seem plausible but does not correctly represent the death rate calculation provided.
- **Option D:** This option does not seem directly related to standard epidemiological calculations for death rate or case fatality rate based on the provided numbers.

## Clinical Pearl / High-Yield Fact
A key point to remember is the distinction between **death rate** (or mortality rate) and **case fatality rate**. The death rate is a measure of the total number of deaths in a population, while the case fatality rate is the proportion of deaths within a designated population of people with a particular condition over a certain period of time. Understanding the difference is crucial for accurately interpreting epidemiological data.

## Correct Answer Line
**Correct Answer: D. 10.**