Which explains how root-tip wedging can weather a rock?
a.
in root-tip wedging, dead material from plant roots breaks down into acids that get into cracks and dissolve the rocks.
b.
in root-tip wedging, plant roots get into cracks and secrete acids, which freeze and break apart the rocks.
c.
in root-tip wedging, plant roots get into cracks and secrete water, which freezes and breaks apart the rocks.
d.
in root-tip wedging, plant roots get into cracks, grow, and break apart the rocks.