Answer:
Second Generation: transistors
Third Generation: integrated circuits
First Generation: vacuum tubes
Step-by-step explanation:
Generations of computers are categorized based on the technologies that were used in them.
Given innovations or technologies are:
transistors :
Transistors were introduced in the second generation in place of vacuum tubes.
integrated circuits :
Integrated circuits were introduced in the third generation. An IC consists of multiple transistors.
vacuum tubes:
The very first generation of computers used vacuum tubes to do the calculations. the only drawback was that the tubes used to heat up very soon.
Hence,
Second Generation: transistors
Third Generation: integrated circuits
First Generation: vacuum tubes