Answer: The correct option is A (Segmentation waves; food to move backward and forward; peristalsis; food to move along the tract distally).
Step-by-step explanation:
Gastrointestinal motility is defined as the different activities carried out by the smooth muscles of the tract which Involves it's contraction and relaxation to bring about the movement of ingested food through the gut for absorbing nutrients, water,electrolytes and eliminating waste products. These movements can be divided into two namely:
--> Mixing Contractions: These contractions are also called the SEGMENTATION WAVES. When a portion of the small intestine becomes distended with chyme, stretching of the intestinal wall elicits localised concentric contraction spaced at interval along the intestine causing segmentation of the small intestine. These contraction causes the movement of chyme BACKWARD and FORWARD which allows greater mixing with the secretions of the intestines.
--> Propulsive Contractions: These contractions are also called peristaltic waves. Bands of muscles in the walls of the gastrointestinal tract contract and relax alternately to push each bolus of food downwards slowly. This process is known as PERISTALSIS. This occurs in all regions of the tract causing the movement of food towards the anus (distal direction).
Therefore, gastrointestinal motility includes Segmentation waves which causes food to move backward and forward, and peristalsis; which causes food to move along the tract distally.