**Question:** According to American Heart Association & World Heart Federation 2015 criteria, low risk is defined as having an Acute Rheumatic Fever incidence <---------- per 100,000 school aged children per year? A. 20 B. 50 C. 100 D. 1000 **Core Concept:** Acute Rheumatic Fever (ARF) is a complication of streptococcal pharyngitis and is characterized by inflammation of the heart, joints, and central nervous system. The 2015 American Heart Association and World Heart Federation guidelines define low-risk areas as those with a low incidence of ARF, which is usually <20 cases per 100,000 school-aged children per year. **Why the Correct Answer is Right:** The correct answer, D, is chosen because it represents the lower end of the range for ARF incidence in low-risk areas, as stated in the guidelines. Acute Rheumatic Fever incidence should ideally be less than 20 cases per 100,000 school-aged children per year to qualify a region as low-risk. **Why Each Wrong Option is Incorrect:** A) 20 cases per 100,000 school-aged children per year is too high and does not meet the criteria for low-risk areas. B) 50 cases per 100,000 school-aged children per year is still higher than the required threshold, making it incorrect. C) 100 cases per 100,000 school-aged children per year is too high, qualifying it as a high-risk area rather than a low-risk area. **Clinical Pearl:** The distinction between low-risk and high-risk areas for Acute Rheumatic Fever is crucial as it influences the preventive strategies and management guidelines. In low-risk areas, preventive measures are less stringent, while in high-risk areas, more extensive preventive strategies are implemented. **Correct Answer Explanation:** According to the 2015 guidelines from the American Heart Association and World Heart Federation, a low-risk area for Acute Rheumatic Fever should have an incidence of less than 20 cases per 100,000 school-aged children per year. This definition is essential for defining the preventive strategies and management guidelines to be implemented in that region.