## Core Concept
The problem involves calculating the total number of blind individuals under the age of 16 in a district. This requires understanding population demographics and prevalence rates. The **prevalence of a disease** is defined as the total number of cases of the disease in the population at a given time.

## Why the Correct Answer is Right
To find the total number of blind individuals under 16, we first need to calculate the population under 16 and then apply the prevalence of blindness to this population. Given:
- Total population = 10 lacs = 1,000,000
- Percentage of population under 16 = 30%
- Prevalence of blindness among under 16 population = 0.8/1000

Population under 16 = 30% of 1,000,000 = 0.3 * 1,000,000 = 300,000

Prevalence of blindness = 0.8/1000 = 0.8 / 1000 * 300,000 = 240

## Why Each Wrong Option is Incorrect
**Option A:** Without calculation, we cannot assume this is correct or incorrect directly, but let's evaluate other options.
**Option B:** Similarly, direct evaluation is not possible without calculation.
**Option C:** This option suggests a calculation; let's verify if it matches our calculation.
**Option D:** This seems to directly provide a number; let's see if it aligns with our approach.

Given our calculation yields 240, any option not matching this is incorrect.

## Clinical Pearl / High-Yield Fact
When solving epidemiology questions, always break down the problem into steps: identify the population at risk, understand the prevalence or incidence rate provided, and apply it correctly to find the number of cases. Remember, **prevalence** includes both new and existing cases, whereas **incidence** refers to new cases.

## Correct Answer: B. 240.