This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Communicable diseases, Subject name: Social & Preventive Medicine
In a town with population of 100,000 the number of slides examined is 5000. Out of these, 100 slides were postive for malaria. The API is? 
Select and explain. 
A. 2, B. 5, C. 1, D. 0.5
C: 1
Answer: C: 1 
Explanation: Annual parasite incodence = Confirmed cases during 1 year / population under surveillance x 1000 ie 100/ 100000 x 1000 = 1% Reference; Park&;s Textbook of preventive and social medicine, 24th edition.Pg no. 278