This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Gastro-Intestinal Tract, Subject name: Pharmacology
A 46-year-old male presents to OPD with diarrhea and abdominal pain. On investigations, it was found to be non-infective and you proceed with diphenoxylate therapy in this patient. Which of the following is the primary target for the drug you prescribed to this patient? 
Select and explain. 
A. Secretion, B. Digestion, C. Inflammation, D. Motility
D: Motility
Answer: D: Motility 
Explanation: Diphenoxylate - is an opioid - it binds to mu receptors in the GIT - works by slowing motility of GIT.