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: Social & Preventive Medicine
Secular trend is: 
Select and explain. 
A. Trend over sho passage of time, B. Trend over long passage of time, C. Periodic changes, D. Sudden explosive changes
B: Trend over long passage of time
Answer: B: Trend over long passage of time 
Explanation: Trend over long passage of time