I believe none of these options are correct. However, if you had to choose one, I would pick A - <span>Nina slid into her seat just as the bell rang and tried to catch her breath.
B, C, and D are incorrect because these are all examples of direct characterization, meaning that the other directly tells us what these people are like. This doesn't happen in A, which is why I would choose that option.
</span>
The correct answer is Beowulf/the dragon.
Beowulf is the main character in the epic poem "Beowulf," which means that he is the protagonist. Antagonist is a bad character, who is usually the protagonist's worst enemy. In the beginning of the poem, the antagonist was Grendel, but at the end, it was the dragon.
To clearly state the main idea. The main idea is the reason for your paper. Hope this helps! :)