Question 4 (5 points) Listen Please identify the best explanation for the following Snort detecting rule. alert top $HOME_NET any -> $HOME_NET any (msg: "nmap tcp ping"; flags: A; ack: 0;) an alert is raised as long as a top packet with sequence number zero is sent from our home network to any host of external network. an alert is raised as long as a udp packet with ack number zero is sent from our home network to any host of external network. an alert is raised as long as a top packet with ack number zero is sent from any host of external network to our home network. an alert is raised as long as a tcp packet with ack number zero is sent from our home network to any host of external network