A dental laboratory has returned a removable partial denture framework. The framework fit the master cast well but when tried in the mouth, a stable fit could not be achieved. The possible cause(s) of the problem is/are
1. distortion in the final impression.
2. insufficient retention.
3. improper pour of the master cast.
4. casting error.

(2) and (4)

(1) and (3)

(1) (2) (3)

All of the above

(4) only