Answer : 4. "First Generation"
Explanation :

Answer: D) First Generation Explanation: The First Generation Computers size was very large.    Since the First generation computers used 1000s of vacuum tubes that required lot of space made them gigantic in size. Single transistor could replace 1000 vacuum tubes and a single IC chip replaced 1000s of transistors made computers smaller and more speedy.   It is obvious that computers developed with more power, reliability, speed and smaller sizes due to the enhancement of technology.