The answer would be D, empathy
Option A would be incorrect since the word avarice means greediness. It could fit in the sentence however it would be used incorrectly since they wouldn’t feel greed for the seagulls.
Option B would also be incorrect since the meaning of the word apathy means lack of motivation or something that wouldn’t concern you since it wouldn’t be important or apply to you. Since they were imagining that they could fly like seagulls then it has been brought to their attention and it would be incorrect.
Option C means the hatred of women. Since this question has nothing to do with women since it it talking about birds and seagulls then this option would be incorrect.
Optio D however would be the correct answer since empathy means to share feelings or longing for something. Since the seagulls understand how the birds feel they can relate to one another therefore this answer would be correct.
Hope this helps! :3