The answer is A - Computers were drastically reduced in size.
Transition from 1st generation to 2nd generation computers took a while. There was an all-round development in designs and technology. The birth of transistor technology formed electronic switches. One major advantage of transistor technology was the size. Transistors were usually very small in size as compared to tubes and this resulted in drastic reduction of computer sizes. Due to the reduction of size, transistors were easy to handle and maintain than vacuum tubes .