In-Text Figure Based Questions
-Why do circular muscles contract behind the bolus while longitudinal muscles contract ahead of the bolus?(Figure 24-4)

A) Circular muscles contract behind the bolus to close the sphincters while longitudinal muscles contract ahead of the bolus to open the sphincters.
B) Circular muscles contract behind the bolus to open the sphincters while longitudinal muscles contract ahead of the bolus to close the sphincters.
C) Circular muscles contract behind the bolus to push the bolus forward while longitudinal muscles contract ahead of the bolus to shorten that segment of the digestive tract.
D) Circular muscles contract behind the bolus to shorten that segment of the digestive tract while longitudinal muscles contract ahead of the bolus to push the bolus forward.
E) Circular muscles contract behind the bolus to mix the contents while longitudinal muscles contract ahead of the bolus to activate stretch receptors in the wall of the digestive tract.