I think They were experienced in construction for part A
Adding -s is the most common. for example: books, cups, pencils, etc. -es might have been the one that confused you, but that isn't a super common ending for plurals--instead, a more common one would be "-ies" which is when you drop the y (berry becomes berries, for example).
Answer:
Its A
Explanation:
Because the plot element explains their emotions
