Final answer:
A conjunction is the part of speech that links a compound subject and a compound predicate.
Step-by-step explanation:
The part of speech that links a compound subject and a compound predicate is a conjunction. A conjunction is a word that connects words, phrases, or clauses. In this case, a conjunction can be used to link multiple subjects or predicates together in a sentence. For example, in the sentence 'Sara and Tom went to the store and bought some groceries,' the conjunction 'and' links the compound subject 'Sara and Tom' with the compound predicate 'went to the store and bought some groceries.'
Learn more about Parts of speech