Which of the following attack types can be used to compromise the integrity of data during transmission?

Keylogging captures keystrokes at the endpoint device before data is transmitted, so it compromises confidentiality at the source rather than data integrity during transmission.

Packet sniffing involves intercepting and capturing data packets as they traverse a network, directly targeting data during transmission. While packet sniffing is primarily associated with confidentiality attacks, when combined with techniques like man-in-the-middle positioning, captured packets can be modified and reinjected, compromising the integrity of data in transit. Among the given options, it most directly operates on data during transmission, making it the best answer for compromising integrity of transmitted data.

Synchronization (SYN) flooding is a denial-of-service attack that overwhelms a target with TCP SYN requests, affecting availability rather than the integrity of transmitted data.

Session hijacking takes over an established session between two parties, which primarily compromises authentication and authorization rather than directly altering data integrity during transmission.