Which minimization for the KMAP is correct
Consider:

For Case 1:

A = 0

B = X

C = 1

Solution = 1

But AC = 0

Wrong

For Case 3:

A = X

B = 1

C = 1

Solution = 1

But B'C = 0

Wrong

If you are not using all your "true" solutions in the formulation then bizarre things start to happen :)