The correct answer is option 'D' - Fourth. Let's discuss the details below:

The microprocessor is a central processing unit (CPU) that integrates the functions of a computer's central processing unit onto a single integrated circuit (IC). It is often referred to as the "brain" of a computer. The development of the microprocessor revolutionized the field of computing and paved the way for the modern digital age.

Here is a breakdown of the different generations of microprocessors:

First Generation:
The first generation of microprocessors was not commercially available. However, the concept of a microprocessor was introduced in the early 1970s. The microprocessors developed during this time were relatively simple and had limited capabilities.

Second Generation:
The second generation of microprocessors, also known as 8-bit microprocessors, was introduced in the mid-1970s. These microprocessors had improved performance and capabilities compared to the first generation. They were used in early personal computers, such as the Intel 8080 and the Motorola 6800.

Third Generation:
The third generation of microprocessors, also known as 16-bit microprocessors, was introduced in the late 1970s and early 1980s. These microprocessors had further improved performance and capabilities compared to the second generation. They were used in more advanced personal computers and other computing devices.

Fourth Generation:
The fourth generation of microprocessors, also known as 32-bit microprocessors, was introduced in the mid-1980s. This is the generation in which the microprocessor was first launched. The introduction of 32-bit microprocessors brought significant improvements in processing power, efficiency, and capabilities. These microprocessors were used in a wide range of applications, including personal computers, gaming consoles, and embedded systems.

Fifth Generation:
The fifth generation of microprocessors, also known as 64-bit microprocessors, was introduced in the early 2000s. These microprocessors further improved processing power and capabilities compared to the fourth generation. They are commonly used in modern personal computers, servers, and high-performance computing systems.

In summary, the microprocessor was first launched in the fourth generation, which is why the correct answer is option 'D' - Fourth.