In CEH v13 Module 03: Scanning Networks, under the Nmap Host Discovery Techniques, TCP SYN ping scan is explained as one of the methods used to determine whether a host is online by sending SYN packets to specified TCP ports.

When using Nmap:

-PS specifies a TCP SYN ping scan. It sends SYN packets to a given port (by default port 80, unless specified) to check whether a host is up and whether the port is open.

The response type to this SYN packet determines the host status:

If a SYN/ACK is received, it indicates the port is open, and the host is up.

If RST is received, the port is closed, but the host is still considered online.

If no response or ICMP unreachable is received, the host may be down or filtered.

Clarification of options:

A. -pp: This is not a valid Nmap option.

B. -PO: This sends IP Protocol Ping, used less frequently and not the same as SYN ping.

C. -PS: Correct. Performs a TCP SYN Ping Scan.

D. -PA: Sends TCP ACK Ping, used to determine firewall presence but not the same as SYN scan.

Reference from CEH v13 Study Guide and Course Material:

CEH v13 Official Module 03 – Scanning Networks, Slide: Nmap Host Discovery Techniques

EC-Council iLabs - Scanning Networks Practical Lab Guide: Section on nmap -sn -PS

Nmap Official Documentation (also referenced in CEH): https://nmap.org/book/man-host-discovery.html