A latecomer joins the prayer leader in Ruku of the third Witr rak'ah. What is the Qunut ruling when completing missed rak'ahs?

Witr: Structure, Qunut, Missed Qunut, and Ramadan Congregation

• He is treated as having caught the Qunut and does not repeat it later.
• He must repeat Qunut in every missed rak'ah.
• His Witr is automatically invalid.
• He must begin a separate congregational prayer.