Question 15 "A number of microprocessors at its CPU" is an apt description of a:

A micro-computer is a complete computing system built around one or more microprocessors, integrating the CPU with memory, I/O controllers, and other supporting components. A microprocessor is just the CPU chip itself, a micro-controller is a specialized embedded processor, and a micro-transistor is a basic electronic component—none describe a system containing multiple microprocessors as its CPU component.

Step-by-step Derivation:
The question asks what device has 'a number of microprocessors at its CPU.' Breaking down the terminology: (1) A microprocessor is a single CPU chip. (2) A micro-computer is a complete computer system that includes microprocessor(s) as its central processing unit, along with memory, I/O interfaces, and other subsystems. (3) A micro-controller is a single-chip embedded system for specific control tasks, not typically multiple microprocessors. (4) A micro-transistor is an individual electronic component, not a computing system. Therefore, B (Micro-computer) is the correct answer as it describes a system architecture where microprocessors form the CPU core.