When the plot of a story includes the main character’s internal conflict, which of the following may be true?
the theme concerns an emotionally uplifting topic.
the main characters are not relatable for the audience.
the protagonist and the antagonist are the same.
the conflict becomes external when the main character matures.

The protagonist and the antagonist are the same.

Explanation:

When the plot of a story focuses on a character's internal conflict, we can assume that the protagonist and the antagonist are the same. The protagonist of a story is the main character. The antagonist, on the other hand, is the person who is at conflict with the protagonist. In this case, as the conflict is one of man vs. himself, both the protagonist and the antagonist are the same.

faulty parallelism is a construction in which two or more parts of a sentence are equivalent in meaning but not grammatically similar in form.

the correct version of this faulty parallelism in the sentence is:

the hikers knew that the hike was six miles, that it usually required the entire day, and it would not be wise to start after 10: 00 a.m.

the problem is the last sentence, the first two have a basic subject+verb+object structure.

so, to give a proper balance to the structure, or better said, to give a parallel structure, we must write a basic s+v+o structure in all three sentences:

the hikers knew that the hike was six miles, that it usually required the entire day, and it would not be wise to start after 10: 00 a.m.

the answer should be d) he was one of those young thousands who greeted the war with a certain amount of relief, welcoming the liberation from webs of tangled emotion" since it is the best option because it shows his desire to free himself. 

hope this answer you! have a great day.