Explanation:

- PV Sindhu clinched the silver medal at the December 2021 BWF World Tour Finals in Bali, Indonesia. She is a highly accomplished Indian badminton player, known for her numerous international victories, including an Olympic silver and bronze medal.

- Aakarshi Kashyap is a young Indian badminton player who has shown potential in national and international competitions but did not win a medal at the 2021 BWF World Tour Finals.

- Mugdha Agrey is another talented Indian shuttler; however, like Kashyap, she did not achieve a podium finish at the 2021 event in Bali.

- Saina Nehwal is a veteran Indian badminton player and former World No. 1. While she has a storied career, including multiple international accolades, she did not win a medal at the 2021 BWF World Tour Finals.

Correct Answer: Option 4: PV Sindhu