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
. A village has a total of 100 under-five children. The coverage with measles vaccine in this age group is 60%. Following the occurrence of a measles case in a child after a visit outside, twenty six children developed Of measles is - measles. The secondary attack rate 
Select and explain. 
A. 0.25, B. 0.4, C. 0.5, D. 0.65
D: 0.65
Answer: D: 0.65 
Explanation: None