This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: VBDs, Arboviral & Viral Infections, Surface Infections, Subject name: Social & Preventive Medicine
A population of 100000 is under surveillance during a year. 100 cases were positive for malarial thick smear. 20 developed complications and 10 died among cases. What is the Annual parasite incidence? 
Select and explain. 
A. 1 per 1000, B. 2 per 1000, C. 10 per 1000, D. 20 per 1000
A: 1 per 1000
Answer: A: 1 per 1000 
Explanation: API= 1 per 1000 API ( annual parasitic incidence) 1. Best indicator of malaria control 2. ABER >= 10 % 3. API >= 2 - high risk area