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.
Keep in mind that a compound predicate has two or more verbs.
Based on that information alone, we can eliminate A and B. With C, this one seems like it could work, but it actually doesn't. The verb in that sentence is "enjoy", and in this case, "skiing" and "skateboarding" are nouns. (because they're the object of the predicate verb.) That leaves D as the answer!
Hope I helped! :)
tl;dr: The answer is D!
I would just go to spark notes. If you go there and find any that you think may be significant, come back here and I will tell you their meaning.
A clear, concise viewpoint
engaging images
a call to action
text that is easy to read
an appropriate style of text
evidence to support the viewpoint
