Which invention helped make computers smaller and faster?  

Correct answer - option D (integrated circuit) was the invention that helped make computers smaller and faster.
Integrated circuit are also known as chip or microchip. It is made from semiconductive material, the most commonly material used is silicon. Integrated circuit carry millions of tiny transistors, resistors and capacitors.

This has made it easy for computers to be made smaller and faster. It is used for many functions. It can serve as a computer memory, microprocessor, oscillator, amplifier, timer and several other functions. Integrated circuit is classified into analog, digital and mixed signal (which has analog and digital signaling on the same chip).