GOALIE is the appositive in the sentence
Well an exposition is a <span> comprehensive description and it explains an idea or theory.
So I'm going to go with D. </span>
Gloat in the sentence means to brag. Basically, the third selection. "To make fun of someone."
Hopefully this helps :)
That emotions is : Excitement
Since according to the information that he heard, Struldbrugs are immortal. This make Gulliver really excited and want to investigate the immortality