Final answer:
The correct command to capture traffic from a specific IP address using tcpdump and save it to a file on the eth0 interface is 'tcpdump -i eth0 -w src host '.
Step-by-step explanation:
The command to use tcpdump to capture traffic from an IP address on the interface eth0 and output the results to a file is B) tcpdump -i eth0 -w <filename> src host <IP-address>. Here, -i eth0 specifies the interface eth0, -w <filename> indicates that the captured packets should be written to a file. You need to replace '<filename>' with the actual file name where you want to save the output and '<IP-address>' with the IP address you are interested in capturing traffic from.