One TB infected person can infect how many people in 1 year?

## Core Concept
The question tests understanding of the transmission dynamics of Tuberculosis (TB), specifically the infectiousness of an untreated or active TB case. TB is a major global health problem, and its spread depends on several factors including the infectiousness of the individual, the presence of susceptible individuals, and environmental factors.

## Why the Correct Answer is Right
One person with active TB can infect approximately 10-15 people in a year if left untreated. This estimate can vary based on factors such as the individual's coughing pattern (more infectious if coughing up bacilli), the presence of drug-resistant TB, and the population's immunity and screening practices. The bacteria are primarily spread through airborne transmission when an infected person coughs, sneezes, or talks.

## Why Each Wrong Option is Incorrect
- **Option A:** This option suggests a much lower number of infections per year. While it's true that not everyone exposed to TB will become infected, and the actual number can vary widely based on several factors, 1-2 people is on the very low side for an estimate of secondary infections from a single untreated active TB case over a year.
- **Option B:** This option suggests a higher number but still underestimates the potential. However, without the exact figure provided, we can't directly refute it based on standard knowledge, but we know 10-15 is a commonly cited estimate.
- **Option D:** This option suggests a significantly higher number. While super-spreaders can exist in TB (as in other infectious diseases), the average number for a typical untreated active TB case is not usually quoted this high.

## Clinical Pearl / High-Yield Fact
A key point to remember is that individuals with active TB are most infectious until they have been on effective antibiotic treatment for at least two weeks. This is why isolating patients with active TB and starting treatment promptly are critical public health measures. Screening and treating latent TB infection in high-risk populations can also prevent progression to active disease.

## Correct Answer: C. 10-15.