In which of the following case it was held by the Supreme Court of India that the National Green…

In Municipal Corporation of Greater Mumbai v. Ankita Sinha (2021), a three-judge bench of the Supreme Court held that the National Green Tribunal is a special forum and can take up environmental matters suo motu, for example on letters or news reports, in exercising its powers under the National Green Tribunal Act, 2010.

M.C. Mehta v. Union of India is a series of environmental public interest cases decided by the Supreme Court itself, not a ruling on the Tribunal's suo motu power.