Karen Was Running Port Scans on Each Machine of Her

Karen was running port scans on each machine of her network in order to identify suspicious ports on the target machines. She observed the following results during the port scan of a particular machine.

A) Some of the ports were not being acknowledged, i.e. no acknowledgment from the target machine II. Some ports were responding with SYN + ACK packets III. Some ports were responding with an RST packet What should she interpret for the ports that did not return the acknowledgement?
B) She should that those ports as Closed ports
C) She should that those ports as Open ports
D) She should that those ports as Stealth ports
E) She should that those ports as Half Open ports