Introduction:
Plotters are devices used to draw or print graphics, typically used in engineering, architecture, and design applications. They are different from printers because they use pens or other writing instruments to create precise and accurate drawings. However, some modern plotters have evolved to use jets of ink instead of pens, providing faster and more efficient plotting capabilities.

Explanation:
The type of plotter that uses jets of ink instead of ink pens is called an inkjet plotter. Let's understand why an inkjet plotter is the correct answer:

1. Inkjet Plotter:
- An inkjet plotter is a type of plotter that uses inkjet technology to create drawings.
- It works by spraying tiny droplets of ink onto the paper or other medium to create the desired image.
- The inkjet technology allows for faster plotting speeds and the ability to produce high-quality color prints.
- Inkjet plotters are commonly used in graphic design, advertising, and other industries where precise and detailed prints are required.

2. Flatbed Plotter:
- A flatbed plotter is a type of plotter that uses a flat surface to hold the paper or other medium during plotting.
- It typically uses pens or other writing instruments to draw on the paper.
- Flatbed plotters are useful for creating large-scale drawings or designs, but they do not use jets of ink.

3. Micrographic Plotter:
- A micrographic plotter is a type of plotter that is specifically designed to create microfilm records or images.
- It uses a combination of optics and mechanical systems to create precise microfilm copies.
- Micrographic plotters do not use jets of ink.

4. Drum Plotter:
- A drum plotter is a type of plotter that uses a rotating drum to hold the paper or other medium during plotting.
- It typically uses pens or other writing instruments to draw on the paper as the drum rotates.
- Drum plotters are known for their high precision and accuracy, but they do not use jets of ink.

Conclusion:
In conclusion, the type of plotter that uses jets of ink instead of ink pens is an inkjet plotter. These plotters provide faster plotting speeds and high-quality color prints, making them suitable for various industries that require detailed and precise prints.

Correct answer is option "B".