20.
A:
Common Cause V/s Union of India (1996) 1 SC 753
B:
Peoples Union of India, AIR 1983 SC 339
C:
Parmanand Katara V/s Union of India, AIR 1989 SC 2039
D:
Lakshmi Kant Pandey V/s Union of India (1984) 25 SC 244
The answer is: C