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
Following are true about coho study, except: 
Select and explain. 
A. Large number of subjects, B. Expensive, C. Suitable for common diseases, D. Less time consuming
D: Less time consuming
Answer: D: Less time consuming 
Explanation: Less time consuming