Final answer:
Julia confesses to Winston that she betrayed him to the Thought Police during their torture. This moment signifies the ultimate destruction of their love and rebellion as both characters succumb to the Party's oppressive tactics.
Step-by-step explanation:
The character Julia from George Orwell's novel '1984' has a critical moment when she reveals something significant to Winston when they meet again after being released from the Ministry of Love. The correct answer to the question, 'What does Julia reveal to Winston when they meet again?' is a) She reveals that she betrayed Winston to the Thought Police.
During their meeting after their respective releases, Julia confesses that under the pressure of torture, she betrayed Winston just as he had betrayed her. This heartbreaking confession indicates that their love and rebellion against the Party were ultimately crushed by the Party's power to manipulate minds and break spirits.
Their relationship at this point is irreparably damaged, and any feelings they might have had for one another are overshadowed by the trauma of their betrayal.