What is a TCP connect scan?

A.
A machine sends UDP request packets to a target to determine which ports are open.

B.
A machine sends ICMP echo request packets to multiple targets to determine which targets are
alive.

C.
A machine sends SYN packets to a target to determine which ports are open. If a SYN ACK is
received from the target, an ACK packet is sent.

D.
A machine sends SYN packets to a target to determine which ports are open. If a SYN ACK is
received from the target, no further packets are sent.