Following loss of a permanent mandibular first molar at age 8, which of the following changes are likely to occur?
1. Distal drift of second premolar.
2. No movement of second premolar.
3. Mesial drift of second permanent molar.
4. No movement of second permanent molar.

(1) and (3)

(1) (2) (3)

(2) and (4)

(4) only

All of the above.