Which of the following Bluetooth hacking techniques does an attacker use to send messages to users without the recipient's consent, similar to email spamming?

Bluesmacking is a Denial of Service attack that sends oversized Bluetooth packets (similar to a Ping of Death) to crash or freeze the target device.

Bluesniffing refers to passively capturing and monitoring Bluetooth radio traffic using a compatible adapter and packet analyzer.

Bluesnarfing involves unauthorized access to and theft of data (contacts, messages, calendars) from a Bluetooth device by exploiting vulnerabilities in the OBEX protocol.

Bluejacking exploits the Bluetooth OBEX Push profile to send unsolicited contact cards or messages to discoverable devices in range, analogous to spam in that the recipient receives unwanted content without approval. It does not grant the attacker access to device data - it is purely a nuisance/social engineering vector that leverages Bluetooth's device discovery and messaging features.