Concept:EDSAC is an early computer that used the stored-program concept.
Explanation:EDSAC stands for Electronic Delay Storage Automatic Calculator.
It was one of the first computers to run programs stored in memory.
In the stored-program concept, both instructions and data are held in the computer's memory.
This made it easier to change programs without rewiring the machine.
Circuit switching, packet routing, and packet switching relate to communication networks, not computer architecture.
Therefore, the correct concept is the stored program.
Answer:D. Stored program