## **Core Concept**
The World Health Organization (WHO) provides guidelines for the assessment of respiratory rate in children to help identify pneumonia and other severe respiratory illnesses. For children under 2 months, a fast breathing rate is an indicator of potential respiratory distress or infection.

## **Why the Correct Answer is Right**
For children less than 2 months old, the WHO criteria define fast breathing as a respiratory rate of more than 60 breaths per minute. This threshold is critical because infants, especially those under 2 months, have a higher baseline respiratory rate compared to older children and adults. A rate above 60 breaths per minute in this age group may indicate respiratory distress, pneumonia, or another serious condition that requires immediate medical evaluation.

## **Why Each Wrong Option is Incorrect**
- **Option A:** 40 breaths per minute is considered normal for children under 2 months and does not indicate fast breathing.
- **Option B:** 50 breaths per minute, while on the higher side for some infants, is not the defined threshold for fast breathing in children under 2 months.
- **Option D:** 70 breaths per minute is indeed a high respiratory rate but the specific threshold for defining fast breathing in children under 2 months is more than 60 breaths per minute.

## **Clinical Pearl / High-Yield Fact**
A key point to remember is that the definition of fast breathing varies by age: more than 60 breaths per minute for children under 2 months, more than 50 breaths per minute for children 2-12 months, and more than 40 breaths per minute for children 1-5 years. Recognizing these thresholds can aid in the early identification and management of respiratory illnesses.

## **Correct Answer:** C. 60 breaths per minute.