A typical modern computer uses

LSI chips
Vacuum tubes
Valves
All the above E. None of the above

The correct answer is: A. LSI chips.

LSI chips are large-scale integrated circuits that contain millions or even billions of transistors. They are used in a wide variety of electronic devices, including computers, smartphones, and cars.

Vacuum tubes are electronic components that were used in early computers. They are now obsolete, having been replaced by LSI chips and other solid-state devices.

Valves are devices that control the flow of fluids. They are not used in computers.

Therefore, the correct answer is A. LSI chips.