The correct option is D Balbir Singh
Balbir Singh took on a project to rejuvenate the Kali Bein river. The river stretched almost 160 km and was filled with waste materials, reducing its size over the decade. In 2000, Sant Balbir Singh set out to clean the Kali Bein river with a large team of volunteers. He wanted to teach people the importance and benefit of protecting and cleaning the river. After nearly a decade, they managed to restore the river’s natural flow of clean water. Hearing of his efforts, the local government collaborated with Sant Balbir Singh in creating a low-cost sewage system that treats sewage waters for usage in agriculture. For his efforts, Sant Balbir Singh was awarded the Padma Shri award in 2017. He is also known as Eco Baba.