The choice and number of abutments for a fixed partial denture is influenced by the
1. length of the span of the fixed partial denture.
2. crown-root ratio of the abutments.
3. amount of periodontal support of the abutments.
4. position of the abutments in the arch

All of the above.

(1) (2) (3)

(1) and (3)

(2) and (4)

(4) only