Answer:
C. comparative
Step-by-step explanation:
The sentence above is trying to compare the work frequency of the workers in the soup kitchen this year and next year because it used the word, "more." It means that next year, the workers will be working more often than this year.
Also, the sentence used the adverb, "frequently." This adverb has more than two syllables and ends in "y." It is a rule to add "more" prior to the adverb when using it as a comparative adverb.