In which of the rak'ahs of Witr is it necessary (Wajib) to append a Surah after Surah al-Fatihah?

The Witr Prayer: Rulings, Qunut, and Congregation

• Only in the first two rak'ahs.
• Only in the third rak'ah.
• In all three rak'ahs.
• Recitation of a Surah is not Wajib in Witr.