**Core Concept:** Crude death rate (CDR) is a measure of overall mortality rate in a population without considering age distribution. It is calculated by dividing the number of deaths by the mid-year population of the given period and then multiplying by 1000.

**Why the Correct Answer is Right:** The correct answer, option C, refers to the assessment of the population at the end of a specific period, such as a year or a month. The Crude death rate is calculated using the number of deaths that occurred within that period, divided by the mid-year population and multiplied by 1000. This calculation is performed using data obtained at the end of the given time frame.

**Why Each Wrong Option is Incorrect:**

A. Assessing the population at the beginning of the period (Option A) would not give an accurate representation of the current mortality rate, as it does not account for births and deaths that occur throughout the period.

B. Assessing the population at the end of the period (Option C) is the correct method, as it provides an accurate representation of the mortality rate based on deaths that occurred within the given time frame.

D. Assessing the population at any other time point (Option D) would not give the desired result, as the mortality rate is determined by deaths that occurred during the specific time frame, not at any arbitrary point.

**Clinical Pearl:** When calculating mortality rates, it is essential to consider the time frame and assess the population at the end of the period to obtain an accurate representation of the mortality rate. Understanding when to assess the population is crucial for proper analysis of public health indicators and decision-making in healthcare policies and interventions.

**Correct Answer:** C. Assess the population at the end of the period.