The body of the mandible increases in length to accommodate the permanent second molar by

resorption of bone along the anterior border of the ramus and apposition of bone on the posterior border of the ramus

apposition of bone in the condyle.

apposition of bone on the alveolar margin and lower border of the body of the mandible

apposition of bone at the symphysis and posterior border of the ramus of the mandible

anterior growth.