The suggested answer is A, B, D.
The lspci command is used to display information about PCI devices on a system. It can provide details on various aspects of these devices. The command can display device IRQ settings, giving insights into the hardware interrupts assigned to PCI devices. Furthermore, it can show the PCI bus speed, which helps in understanding the data transfer capabilities of the bus. Additionally, it provides device vendor identification, revealing the manufacturers of the PCI devices in the system. Therefore, the three correct pieces of information that lspci can display are device IRQ settings, PCI bus speed, and device vendor identification.