What port scanning method is the most reliable but also the most detectable?

A.
Null Scanning

B.
Connect Scanning

C.
ICMP Scanning

D.
Idlescan Scanning

E.
Half Scanning

F.
Verbose Scanning

Explanation:
A TCP Connect scan, named after the Unix connect() system call is the most accurate scanning method. If a port is open the operating system completes the TCP three-way handshake, and the port scanner immediately closes the connection.