Which type of sniffing technique is generally referred as MiTM attack?

Password sniffing is a passive capture technique that reads credentials from network traffic; it does not involve redirecting or intercepting traffic between two parties.

ARP Poisoning works by sending forged ARP reply packets that associate the attacker's MAC address with a victim's IP address, causing the local network to forward traffic intended for the victim to the attacker instead. This allows the attacker to intercept, read, and optionally forward packets - the defining characteristic of a MiTM attack. All other hosts on the segment update their ARP caches with the spoofed mapping, making the attack transparent to victims.

MAC flooding is an attack that overwhelms a switch's CAM table to cause broadcast behavior, enabling passive sniffing - it does not position the attacker between two communicating hosts.

DHCP sniffing refers to monitoring or rogue DHCP server attacks and does not describe the active traffic-redirection mechanism that defines a MiTM attack.