Transistor was the major technology used during the generation of hardware.

The world would see transistors substitute vacuum tubes in the second generation of computers. The transistor was created at Bell Labs in 1947 but did not see omnipresent use in computers until the late 1950s. 

The transistor enormously higher positioning to the vacuum tube, allowing PCs to transform into littler, speedier, less expensive, more vitality effective and more dependable than their first-generation predecessors. Though the transistor still generated a great deal of heat that subjected the computer to destruction, it was a vast development over the vacuum tube. Second-generation computers still confidence on punched cards for input and printouts for production.

answer(d) sequencing and iteration;