This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Epidemiology, Subject name: Social & Preventive Medicine
What do you understand by the term secular trend- 
Select and explain. 
A. Long term changes, B. Sho long term changes, C. Seasonal Changes, D. Periodical changes
A: Long term changes
Answer: A: Long term changes 
Explanation: The term secular trend implies changes in the occurrence of disease(i.e. A progressive increase or decrease)over a long period of time, generally several years or decade. (refer pg no:66 park textbook 23 rd edition)