Which of the following attack types is being used if the originating IP address has been spoofed?

A ping flood overwhelms a target with ICMP requests but does not inherently involve IP spoofing.

A Trojan is malicious software disguised as legitimate software and is not related to IP spoofing.

In a Smurf attack, the attacker sends ICMP echo requests to a network broadcast address with the source IP spoofed to match the victim's IP address. All hosts on the network reply to the victim, flooding it with traffic. The spoofed source IP is the defining characteristic that distinguishes a Smurf attack from a simple ping flood.

A worm is self-replicating malware that spreads across networks and does not involve IP address spoofing.