A custom HTTP monitor is failing to a pool member 10.

To manually verify a health monitor's "Send String" from the BIG-IP command line, the curl utility is the preferred tool because it allows for custom header insertion.

Matching the Monitor String: The monitor string requires an HTTP/1.1 request which must include a "Host" header. Option A correctly uses the --header (or -H) flag to pass Host: www.example.com to the specific IP and port of the pool member.

Troubleshooting Logic: If curl --header 'Host: www.example.com ' 'http://10.10.3.75:8080/ ' returns a "200 OK" but the BIG-IP monitor still shows "Down," the administrator should check if the Receive String in the monitor configuration matches the output provided by curl.

Invalid Syntax: Option D is incorrect because it tries to append the hostname to the URI path, which the web server will likely reject with a "404 Not Found". tracepath (Options B and C) is a path discovery tool similar to traceroute and cannot validate HTTP response content.