Diagrammatic representation of data refers to the use of visual elements such as diagrams, charts, and pictures to present data in a clear and concise manner. These visual representations help to convey information quickly and effectively, allowing viewers to easily understand and interpret the data being presented.

The correct answer to the question is option 'D', which states that diagrammatic representation of data is done by diagrams, charts, and pictures. This means that all three of these visual elements can be used to represent data in a diagrammatic form.

1. Diagrams:
- Diagrams are graphical representations of data that use symbols, shapes, and lines to show the relationships between different elements or variables.
- They are often used to illustrate the structure, process, or flow of information.
- Examples of diagrams include flowcharts, organizational charts, network diagrams, and Venn diagrams.

2. Charts:
- Charts are visual representations of data that use graphical elements such as bars, lines, or pie slices to display information.
- They are commonly used to compare and analyze quantitative data.
- Examples of charts include bar charts, line charts, pie charts, scatter plots, and histograms.
- Each type of chart is suited for representing different types of data and conveying specific relationships or trends.

3. Pictures:
- Pictures, or images, can also be used to represent data in a diagrammatic form.
- They are often used to convey information in a more visual and intuitive way.
- Pictures can be used to depict real-world objects, scenes, or concepts related to the data being presented.
- They can be especially useful for representing qualitative or subjective data that may not lend itself well to numerical or graphical representations.

In summary, diagrammatic representation of data can be done using diagrams, charts, and pictures. These visual elements help to present data in a visually appealing and easily understandable manner, allowing viewers to quickly grasp the key information and insights conveyed by the data.