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
Phase IV of clinical trials collect information specially about: 
Select and explain. 
A. Drug efficacy, B. Drug potency, C. Drug toxicity, D. Pharmacokinetics of the drug
C: Drug toxicity
Answer: C: Drug toxicity 
Explanation: None