The correct answer is: Spoofing.

• Spoofing: Spoofing specifically refers to the act of imitating a trusted device or user on a network. By creating fabricated packets that appear to originate from a legitimate source, the attacker can gain unauthorized access or disrupt communication flows.

• Replay: A replay attack involves capturing and retransmitting legitimate network traffic to gain unauthorized access or manipulate data. While it utilizes existing packets, it doesn't necessarily impersonate a trusted source.

• Phishing: Phishing attacks attempt to trick users into revealing sensitive information by disguising themselves as legitimate entities (e.g., emails or websites). Spoofing can be a technique used in phishing attacks, but it's not the sole characteristic.

• Forgery: Forgery can encompass a broader range of activities like counterfeiting documents or digital signatures. In the context of network security, spoofing is a more specific term referring to impersonation on a network level.