The correct answer is A) they
Step-by-step explanation:
In grammar, a predicate nominative or predicate noun refers to a word or set of words that are placed after a linking verb (for example, become, be or like) and describe the noun. Additionally, this predicate nominative can be a noun or a pronoun.
According to this, in the sentence "We know that the finalists in the tournament are they" the predicate nominative is the word "they" because this is placed after the linking verb "are" (verb to be) and describes the noun "the finalists" besides this, this predicate nominative is a pronoun or word that replaces a noun.