Why would a device perform an ARP request?

The correct answer is B. To find the destination MAC address for a specific IP address. ARP, or Address Resolution Protocol, is used on IPv4 Ethernet networks to map a Layer 3 IPv4 address to a Layer 2 MAC address. HPE Aruba Networking AOS-CX documentation states that ARP maps network addresses assigned to devices to physical addresses, and specifically maps IPv4 network addresses to Layer 2 MAC addresses on Ethernet networks. When a host wants to send traffic to another IPv4 device on the same local network, or to its default gateway, it must know the destination MAC address to build the Ethernet frame. If the MAC address is not already in its ARP table, it sends an ARP request asking which device owns the target IP address. Option A is incorrect because ARP is not used to find a source IP address. Option C is incorrect because the device already knows its own source MAC address. Option D describes reverse mapping, which is not the purpose of a normal ARP request.