James Watt invented the Rotary Steam Engine.

The Rotary Steam Engine was one of the significant inventions by James Watt. It revolutionized the way power could be generated and utilized during the Industrial Revolution. Here is an explanation of why the correct answer is option 'D':

Background of James Watt:
James Watt was a Scottish engineer and inventor born on January 19, 1736. He is known for his work on improving the efficiency of the steam engine, which played a crucial role in the development of the Industrial Revolution.

Invention of the Rotary Steam Engine:
The Rotary Steam Engine was invented by James Watt in 1781. It was an improvement upon the Newcomen steam engine, which was inefficient and consumed a large amount of coal. Watt's invention made significant advancements in the design and efficiency of steam engines.

Working Principle of the Rotary Steam Engine:
The Rotary Steam Engine was designed to convert steam power into rotary motion. It utilized a rotary motion mechanism, different from the reciprocating motion of the Newcomen engine. The engine consisted of a steam cylinder, a piston, and a crankshaft. As steam was admitted into the cylinder, it pushed the piston, causing the crankshaft to rotate. This rotary motion could be used to power various machines and equipment.

Advantages of the Rotary Steam Engine:
The Rotary Steam Engine had several advantages over its predecessors, making it a significant innovation during the Industrial Revolution:

1. Increased efficiency: Watt's design improved the efficiency of steam engines, reducing fuel consumption and increasing power output.

2. Versatility: The rotary motion produced by the engine allowed it to power a wide range of machinery, such as mills, factories, and transportation systems.

3. Industrial applications: The Rotary Steam Engine played a crucial role in powering the machinery of the Industrial Revolution, contributing to the rapid growth of industries and manufacturing processes.

4. Economic impact: The increased efficiency and versatility of the Rotary Steam Engine led to significant economic growth by enabling the mechanization of various industries and reducing labor requirements.

Legacy of James Watt:
James Watt's inventions, including the Rotary Steam Engine, had a profound impact on the development of modern industry and technology. His improvements to the steam engine laid the foundation for the Industrial Revolution and transformed the way power was generated and utilized.

In conclusion, James Watt invented the Rotary Steam Engine, which revolutionized the efficiency and applications of steam power during the Industrial Revolution.