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
The changes occuring in the disease frequency over many years is called - 
Select and explain. 
A. Cyclic trend, B. Seasonal trend, C. Secular trend, D. None of the above
C: Secular trend
Answer: C: Secular trend 
Explanation: None