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: Medicine
Window period for thrombolysis in a stroke patient is: 
Select and explain. 
A. 1.5 hours, B. 2.5 hours, C. 3.5 hours, D. 4.5 hours
D: 4.5 hours
Answer: D: 4.5 hours 
Explanation: Answer- D. 4.5 hours"Intravenous thrombolysis is usually practiced within the window period of 4.5 hours.