The sentence that uses the verbs correctly is: The Land of Horses demonstrates the importance of the West in the history of the U.S. This sentence uses the singular form of the verb "demonstrates" because the subject that agrees with it is also singular. The subject "The Land of Horses" is a title of a written article or book, and therefore, should take the singular form of the verb.
Change numbers to two
Divide by five
I think he was running from the ghost
"In" -- not
"terminable" -- able to be ended
Interminable -- not able to be ended
Thus:
Interminable -- seemingly endless
