Jesus Christ only — everything that points at him counts. His names (Jesus, Christ, Messiah), his titles (Redeemer, Lamb of God, Holy One of Israel, and “the Lord” or “God” where the passage means him), the symbols that stand for him — the rock, the light, the true vine — and every pronoun whose antecedent is him: he, him, his, thee, and his own I and me where he is the one speaking.

Heavenly Father as a separate person, the Holy Ghost, and every prophet in the chapter are not references — picking one costs you.