Concept:Computer generations are classified by the main electronic component used in their circuits.
Explanation:The first generation used vacuum tubes.
The second generation used transistors.
The third generation used integrated circuits, or ICs.
The fourth generation used Very Large Scale Integration, known as VLSI technology.
VLSI made it possible to place an entire central processing unit on a single tiny chip.
This single chip is called a microprocessor.
Therefore, the microprocessor is the main electronic component of fourth generation computers.
This generation is usually dated from around 1971 to 1980.
IBM also produced its first personal computer using a microprocessor in this generation.
Answer:D. fourth generation computers.