What major benefit did integrated circuits bring during the third generation of computers?

Correct answer: Many components could be placed on a chip, improving size and speed

The governing technological change in the third generation was the replacement of individual transistor assemblies with integrated circuits, in which multiple electronic components were fabricated on a single semiconductor chip. This greater integration reduced the physical size of computers, improved reliability, lowered power and heat demands, and generally increased processing speed. Therefore option A is correct. Computers did not become completely mechanical, so B contradicts the electronic nature of the period. An abacus is an ancient manual calculating device and was not a defining component of third-generation computers, ruling out C. Punch cards could be used for input or storage, but they did not become the main electronic memory, so D is also incorrect.