To solve this question, the user needs to have knowledge about computer hardware and specifically about the IRQ (Interrupt Request) system.

The IRQ system is used by devices to communicate with the CPU (Central Processing Unit) and request its attention. Each device is assigned a specific IRQ number to ensure proper communication and coordination.

COM1 is a standard serial port used for connecting peripherals such as modems or serial mice. In the IRQ system, COM1 commonly uses IRQ 4.

Let's go through each option and explain why it is right or wrong:

A. 3: This option is incorrect because COM1 commonly uses IRQ 4, not IRQ 3.

B. 4: This option is correct. COM1 commonly uses IRQ 4.

C. 6: This option is incorrect because COM1 commonly uses IRQ 4, not IRQ 6.

D. 7: This option is incorrect because COM1 commonly uses IRQ 4, not IRQ 7.

E. 14: This option is incorrect because COM1 commonly uses IRQ 4, not IRQ 14.

The Answer is: B