Which one of the following cases is not related to the doctrine of severability?

Minerva Mills Ltd. v. Union of India (AIR 1980 SC 1789) is a landmark decision on the basic structure doctrine and the balance between Fundamental Rights (Part III) and Directive Principles of State Policy (Part IV), wherein Sections 4 and 55 of the Constitution (Forty-second Amendment) Act, 1976 were struck down. By contrast, A. K. Gopalan v. State of Madras (AIR 1950 SC 27), R. M. D. Chamarbaugwalla (RMDC) v. Union of India (AIR 1957 SC 628), and Kihoto Hollohan v. Zachillhu (AIR 1993 SC 412) are leading authorities directly expounding and applying the doctrine of severability to save the valid portions of an enactment after severing an unconstitutional provision.