## **Core Concept**
The question tests understanding of data representation in statistics and graph types. Specifically, it focuses on the types of charts or graphs used to display data, particularly percentages.

## **Why the Correct Answer is Right**
A pie chart is a circular statistical graphic divided into slices to illustrate numerical proportion. In a pie chart, each slice represents a percentage of the whole, making it ideal for showing how different categories contribute to a total. This is why a pie chart is used to depict percentages of data.

## **Why Each Wrong Option is Incorrect**
- **Option A:** A bar chart is used to compare different groups or to track changes over time for more than one group. While it can show percentages, it's not the most intuitive or commonly used graph for depicting percentages of a whole.
- **Option B:** A histogram is a type of graph that represents the distribution of data with the help of rectangles (bars). It is used to show distributions of data and not specifically for percentages of a whole.
- **Option D:** A line graph is used to display information as a series of data points called 'markers' connected by straight line segments. It is one of the basic types of chart used in finance and for other data analysis. The line graph is often used to show trend data or the comparison of two data sets.

## **Clinical Pearl / High-Yield Fact**
A key point to remember is that when you want to show parts of a whole, a **pie chart** is typically the best choice. This is especially useful in epidemiology, healthcare statistics, and research to visually represent percentages of different categories within a dataset.

## **Correct Answer:** C. Pie chart.