## Core Concept
The concept of "poverty lines" is used to determine the minimum level of income required for a person to meet their basic needs. In the context of nutrition, it is often measured in terms of daily calorie intake. The calorie requirements vary between rural and urban areas due to differences in lifestyle and physical activity levels.

## Why the Correct Answer is Right
The correct answer states that the daily calorie intake required in rural areas is **2400 calories**. This is based on the recommendations made by the National Nutrition Institute of India, which suggests that a daily calorie intake of 2400 calories per person is required in rural areas to meet the basic nutritional needs. This requirement is higher than that for urban areas (2100 calories) due to the greater physical activity levels in rural settings.

## Why Each Wrong Option is Incorrect
* **Option A:** 2100 calories - This is the recommended daily calorie intake for urban areas, not rural areas.
* **Option B:** 2600 calories - While calorie needs can vary based on several factors, 2600 calories is not the specified requirement for rural areas.
* **Option D:** 2800 calories - Similar to option B, this is not the standard recommended daily calorie intake for rural areas.

## Clinical Pearl / High-Yield Fact
A key point to remember is that the calorie requirements for rural areas are generally higher than for urban areas due to increased physical activity. The often-quoted figures are 2400 calories for rural areas and 2100 calories for urban areas, which serve as benchmarks for determining poverty lines.

## Correct Answer: C. 2400 calories