F) A reverse shell was used: A reverse shell is a technique that allows a remote attacker to execute commands on a compromised system by opening a connection from the target to the attacker's machine. The image shows that the attacker used the netcat tool to create a reverse shell on host 192.168.1.210, which is running a web server on port 80. The attacker then used the reverse shell to access the /images folder and download a file named secret.jpg.
C) IP address 43.23.10.201 should be blocked at the firewall: IP address 43.23.10.201 is the source of the attack, as shown by the netstat command output in the image. The attacker used this IP address to connect to host 192.168.1.210 on port 80 and exploit a vulnerability in the web server software. Blocking this IP address at the firewall would prevent further attacks from this source.