According to WHO, If a person’s BMI is below 18.5 he/she is classified as __________.

Underweight

The correct answer is Option (2) - Underweight

Body Mass Index (BMI) is a measure used to assess an individual's body weight relative to their height. It is calculated by dividing a person's weight in kilograms by the square of their height in meters (BMI = weight / (height)²).

The World Health Organization (WHO) classifies BMI into several categories to assess the risk of health problems associated with different weight ranges. These categories are:

1. Underweight: BMI less than 18.5
2. Normal weight: BMI between 18.5 and 24.9
3. Overweight: BMI between 25 and 29.9
4. Obesity: BMI 30 or greater

When a person's BMI falls below 18.5, they are considered underweight according to WHO classifications. Being underweight can indicate insufficient body fat and may be associated with health risks such as nutritional deficiencies, weakened immune system, and potential complications during pregnancy.

Therefore, if a person's BMI is below 18.5, they are classified as underweight according to WHO guidelines, not as mentally unfit, blind, or healthy.