If you wanted to deny all Telnet connections to only network 192.168.10.0, which command could you use?

The extended access list ranges are 100-199 and 2000-2699, so the access-list number of 100 is valid. Telnet uses TCP, so the protocol TCP is valid. Now you just need to look for the source and destination address. Only the third option has the correct sequence of parameters. Answer B may work, but the question specifically states "only" to network 192.168.10.0, and the wildcard in answer B is too broad.