We have a list of pairs [("Tariq",71),("Brinda",85),("Shweta",71),("Sunita",85),("Salma",72),("Uday",60)], where each pair consists of a student's name and his/her marks in a course. We sort these pairs in ascending order of marks. Which of the folllowing corresponds to a stable sort of this input?
1. [("Uday",60),("Tariq",71),("Shweta",71),("Salma",72),("Brinda",85),("Sunita",85)]
2. [("Brinda",85),("Salma",72),("Shweta",71),("Sunita",85)("Tariq",71),("Uday",60)]
3. [("Uday",60),("Shweta",71),("Tariq",71),("Salma",72),("Brinda",85),("Sunita",85)]
4.[("Uday",60),("Tariq",71),("Shweta",71),("Salma",72),("Sunita",85),("Brinda",85)]