Who invented the fountain pen, a writing instrument with an internal ink reservoir that feeds ink to the nib?

Introduction / Context:
The fountain pen improved writing convenience by providing a steady flow of ink from an internal reservoir, eliminating the need to dip the pen repeatedly into an inkwell. It became an important tool for students, professionals and writers before the rise of ballpoint pens. This question asks you to identify the inventor most often credited with creating a practical and reliable fountain pen design.

Given Data / Assumptions:

• The device mentioned is the fountain pen with an internal ink reservoir.
• The question focuses on a practical, leak resistant design that became commercially successful.
• The options list inventors from aviation, early pens and bicycle history.
• Only one name is associated with the modern fountain pen in common GK references.

Concept / Approach:
Lewis Edson Waterman, an American insurance broker and inventor, is widely credited with inventing the first reliable fountain pen in the late nineteenth century. His design reduced ink leaks and provided a controlled flow using capillary action. John J. Loud experimented with a ballpoint like pen for marking leather, Sir Frank Whittle is famous for the jet engine, and Kirkpatrick Macmillan is associated with early bicycle development. Thus, in the context of writing instruments, Waterman is the name to remember for the fountain pen.

Step-by-Step Solution:
Step 1: Identify that the question refers to a pen with its own ink supply, which is a fountain pen.Step 2: Recall that Lewis Edson Waterman patented a reliable fountain pen and founded a company to manufacture it.Step 3: Examine the options and find Lewis E. Waterman listed as option D.Step 4: Recognise that Whittle is linked to jet engines, Loud to early ballpoint ideas and Macmillan to bicycles.Step 5: Select Lewis E. Waterman as the correct answer.

Verification / Alternative check:
Histories of writing instruments and pen manufacturing frequently highlight Waterman as the inventor of the successful fountain pen design. The Waterman brand itself became famous for high quality fountain pens. While earlier attempts at self filling pens existed, they were often unreliable; exam oriented GK typically attributes the practical fountain pen to Waterman. None of the other inventors listed are tied to this particular achievement in widely used sources.

Why Other Options Are Wrong:
Sir Frank Whittle played a key role in jet engine development, a field unrelated to writing tools. John J. Loud patent involved a rough ballpoint style device but did not become a popular writing instrument. Kirkpatrick Macmillan is mentioned in connection with early pedal driven bicycles. As a result, none of these individuals invented the fountain pen, so their options are incorrect here.

Common Pitfalls:
A common pitfall is to confuse Waterman with other pen related names or to think that the ballpoint pen and fountain pen were invented by the same person. Another issue is that candidates may overlook the context and choose a famous inventor from a different field. To avoid this, remember the simple link: fountain pen and Waterman, ballpoint pen and Biro, jet engine and Whittle. This approach keeps the associations clear.

Final Answer:
The fountain pen was invented in practical form by Lewis E. Waterman.