Since a Turtle's Shell Essentially Immobilizes the Ribs,how Does the Turtle

Since a turtle's shell essentially immobilizes the ribs,how does the turtle breathe?

A) A turtle resorts to the amphibian system of positive pressure breathing.
B) The turtle has such a low metabolic rate that all oxygen requirements can be met by passive absorption without ventilation mechanisms.
C) The turtle wags its tail to change the volume within the shell and assist ventilation.
D) The turtle draws its shoulder girdle back to exhale and contracts limb flank muscles to inhale.
E) The ribs are allowed a small amount of leeway to move;rhythmic compression of the carapace on the plastron accomplishes this.