The correct answer is B. 3.
COM 2 uses IRQ 3. IRQ stands for Interrupt Request. It is a signal that a device sends to the CPU to request attention. The CPU then interrupts whatever it is doing and handles the request.
COM 2 is a serial port that is used to connect a serial device, such as a modem or a mouse. It is typically used for communication between a computer and a peripheral device.
IRQ 3 is one of the 16 interrupts that are available on a PC. It is used by a variety of devices, including COM 2, the floppy disk drive, and the parallel port.
The other options are incorrect. Option A, IRQ 4, is used by the timer. Option C, IRQ 2, is used by the keyboard. Option D, IRQ 1, is used by the system timer. Option E, None of the above, is incorrect because COM 2 does use an IRQ.