***** NOT A TEACHER *****
You have asked a super difficult question.
(1) First, let's get rid of the "easy" question. "Suggest(s)" does not modify anything. It is the verb for "which."
(2) But what does "which" refer to? Ah! That's the BIG problem. Does it refer to "set suggests" or "words suggest"?
(3) We non-teachers have been warned NOT to answer unless we are pretty confident of our answers. Since I am not
that confident, I can do the following for you, and then you have to make the decision.
(a) Everyone agrees that "set" is a so-called collective noun. That is, if it refers to the whole group, then use the
singular verb; if the emphasis is on the individual members of the group, use the plural verb.
(b) I did some googling and shall now give some examples of the singular use:
"A set of fourteen appendices completes the practicality of the book."
"Each set of 25 papers is two cents."
"A set of words forms a language."
"Choose the word or set of words that best fits the meaning of the sentence as a whole."
(c) Now here are some examples with the plural feeling:
"A set of words arranged so as to display their own interdefinability."
"A set of books which shall clearly and plainly present a complete record."
"Paradigm indicates an unordered set of words which have an identical lexical meaning."
"A set of rules that clarify and delineate how ...."
HAVE A NICE DAY!
Student or Learner