The correct answer is option 3 - Water Burial.

Option 1 - Jonaki Porua is not the correct answer because it did not win the Best Film Award in the Environment Conservation category at the 67th National Film Awards, 2021.

Option 2 - Wild Karnataka is also not the correct answer as it was not the winner of the Best Film Award in the Environment Conservation category at the 67th National Film Awards, 2021.

Option 4 - Ronuwa-Who Never Surrender is not the correct answer either as it did not win the Best Film Award in the Environment Conservation category at the 67th National Film Awards, 2021.

Therefore, the correct answer is option 3 - Water Burial. It was the film that won the Best Film Award in the Environment Conservation category at the 67th National Film Awards, 2021.