A pilgrim is in valid Arafat bounds after zawal on 9 Dhu al-Hijjah but can only make a brief dua. What is correct about the standing?

Book of Hajj: Standing at Arafat, Dhuhr and Asr, and Departure for Muzdalifah

• The length of dua is not a validity condition
• Dua must last exactly one hour
• Climbing the mountain is required
• Without ghusl the boundary is invalid