## Core Concept
The Physical Quality of Life Index (PQLI) is a measure used to assess the quality of life or well-being of a country. It is an average of three basic literacy, infant mortality, and life expectancy at age one.

## Why the Correct Answer is Right
The PQLI is calculated by averaging the literacy rate, infant mortality rate (often expressed as a percentage), and life expectancy at age one. These components are usually expressed on a scale of 0 to 100, making it easier to calculate and understand the index. The correct answer reflects the standardization and scaling used for PQLI components.

## Why Each Wrong Option is Incorrect
- **Option A:** This option does not accurately reflect the scaling or standardization method used for PQLI components.
- **Option B:** Similarly, this option does not correctly represent the performance counting method for PQLI components.
- **Option D:** This option also does not accurately describe the scaling used for the components of PQLI.

## Clinical Pearl / High-Yield Fact
A key fact to remember is that PQLI scores range from 0 to 100, with higher scores indicating a better quality of life. This index was developed to provide a more comprehensive picture of a country's development than economic indicators alone.

**Correct Answer: C. 0 to 100.**