Which of the following tools is used for port scanning?

NSLOOKUP is a DNS query tool used to resolve hostnames to IP addresses and query DNS records, not a port scanner.

NETSH is a Windows command-line utility for configuring and displaying network settings, not a tool for scanning ports.

Nmap (Network Mapper) is the de facto standard port scanning utility, capable of detecting open ports, identifying running services, performing OS fingerprinting, and executing various scan techniques such as SYN, UDP, and ACK scans against target hosts.

L0phtcrack is a password auditing and cracking tool designed to recover Windows credentials, not a port scanner.