**Core Concept**
The graphical representation of frequency distribution curve is used to visualize the distribution of data in a population, illustrating the relationship between the frequency of occurrence and the magnitude of the variable. This concept is crucial in statistics and epidemiology, helping researchers and clinicians to understand patterns and trends in data.

**Why the Correct Answer is Right**
The correct graphical representation of frequency distribution curve is a **Histogram**. A histogram is a type of bar chart that displays the frequency or density of data in a continuous variable. It is created by dividing the data into bins or ranges and then plotting the frequency of each bin on the y-axis against the midpoint of the bin on the x-axis. This representation allows for the visualization of the distribution of data and helps to identify patterns such as skewness, outliers, and normal distribution.

**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because a **Scatter Plot** is used to display the relationship between two continuous variables, not to represent frequency distribution.

**Option B:** This option is incorrect because a **Pie Chart** is used to display the proportion of different categories, not to represent frequency distribution.

**Option C:** This option is incorrect because a **Bar Chart** is used to compare the frequency of different categories, but it does not display the frequency distribution of a continuous variable.

**Clinical Pearl / High-Yield Fact**
A histogram is a powerful tool for visualizing data distribution, and it can help clinicians to identify patterns that may not be evident from numerical data alone.

**Correct Answer: D. Histogram**