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
Disease rate is - 
Select and explain. 
A. Risk of susceptibility, B. Usually expressed a percentage, C. Time period in a calendar year, D. Disease occurrence in a specified time period
D: Disease occurrence in a specified time period
Answer: D: Disease occurrence in a specified time period 
Explanation: Disease rate is a measure of incidence or occurrence of disease in a population.
In other words, it is synonymous for incidence rate.