The correct answer is: A. 9
On the 16-bit ISA bus, IRQ2 is elevated to IRQ9. This is because IRQ2 is a shared interrupt, which means that it can be used by multiple devices. In order to avoid conflicts, IRQ2 is elevated to IRQ9 when it is used by a device. This ensures that each device has its own unique interrupt number.
Option B is incorrect because IRQ11 is not a valid interrupt number on the 16-bit ISA bus. Option C is incorrect because IRQ13 is not a valid interrupt number on the 16-bit ISA bus. Option D is incorrect because IRQ15 is not a valid interrupt number on the 16-bit ISA bus. Option E is incorrect because IRQ2 is elevated to IRQ9, not to none of the above.