To achieve optimum strength and esthetics, a porcelain fused to metal restoration with a porcelain butt joint margin requires a
1. 0.8 - 1.2mm shoulder.
2. sharp, well defined axiogingival line angle.
3. 90?- 100? cavosurface margin.
4. finish line that is 2mm subgingival.

(1) (2) (3)

(1) and (3)

(2) and (4)

(4) only

All of the above