This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Pharmacology
Atropine is added to commercial preparations containing diphenoxylate to: 
Select and explain. 
A. Potentiate its anti-spasmodic effect, B. To reduce excretion of salt and water, C. To prevent overdosage and discourage opioid dependence, D. To prolong its duration of action
C: To prevent overdosage and discourage opioid dependence
Answer: C: To prevent overdosage and discourage opioid dependence 
Explanation: None