Many nineteenth-century American coinages are metaphors. What is meant by dark horse?

a catastrophic event
an unexpected winner
a sign of war or death
a good investment

Respuesta :

A dark horse is an unexpected winner. Someone who wins something completely unexpectedly, out of nowhere, no one would have believed that they would be a winner. The expression was originally used in horse racing as slang to describe a horse that wins that no one would have bet on to win.  

Answer:

an unexpected winner.

Explanation: