The answer is D. It is restarting the thesis.
I think its a predicate hope it helps
<span>"I thought I would be bored by the Shakespeare play, but I was enthralled the whole time"
this is the correct use of the word enthralled as enthralled means to excite and captive the attention of someone or thing, and as you can see in the sentence that he was originally expecting to hate the play, but he uses the word "but" which negates the previous statement and presumably anything followed by the but would be along the lines of him actually liking the play</span>
