The terminus of his progress would be reached when he accomplishes that honour.

Answer: Option C

Beginning : the point in time or space at which something begins.
Highest : of great vertical extent.
Terminal : forming or situated at the end or extremity of something.
Result : a thing that is caused or produced by something else; a consequence or outcome.
Terminus : the end of a railway or other transport route, or a station at such a point; a terminal.

Synonym of Terminus is Terminal