Abbreviations in computing are built from the full name of the component or concept they represent, so the correct expansion must match both the function of the device and the wording actually used in computer science.
CPU stands for Central Processing Unit. It is called "central" because it sits at the core of the computer's operations, coordinating all processing activity, and "processing unit" because its job is to execute instructions and perform calculations.
The other expansions swap in words that sound similar but describe the wrong concept: "control" describes only one internal part of the CPU (the control unit), not the whole component; "computer process unit" and "central personal unit" are not the standard terms used in any textbook or technical reference.
Examination reminder: memorise the exact wording "Central Processing Unit", since abbreviation questions are graded on the precise standard term, not a similar-sounding alternative.
