Step 1: Identify the amendment nicknamed “Mini-Constitution.”
The 42nd Constitutional Amendment Act, 1976 is popularly called the “Mini-Constitution” because it brought one of the most comprehensive overhauls to the Indian Constitution.
Step 2: Understand the scale and scope of changes.
It amended numerous Articles; inserted new Parts/Articles; strengthened the Directive Principles; curtailed certain Fundamental Rights; and altered the balance among the organs of the State.
Step 3: Contrast with the distractors.
- 44th Amendment (1978): Rolled back several Emergency-era changes made by the 42nd, but is not called the Mini-Constitution.
- 46th Amendment (1982): Related largely to sales tax on goods and works contracts—sectoral, not an overhaul.
- 50th Amendment (1984): Narrow changes regarding service matters—limited scope.
Step 4: Conclude.
\[
\boxed{\text{42nd Amendment (Option A) is known as the “Mini-Constitution.”}}
\]