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

## Why the Correct Answer is Right
The PQLI is calculated by taking the average of literacy rate, infant mortality rate (or a transformed version of it), and life expectancy at age one. This index was developed to provide a more comprehensive measure of a country's well-being than GDP alone. It focuses on basic needs and outcomes.

## Why Each Wrong Option is Incorrect
- **Option A:** This option is not provided, but typically, literacy rate is one component.
- **Option B:** Similarly, this option is not provided, but infant mortality is another component.
- **Option C:** Life expectancy at age one is a component.
- **Option D:** Since the actual options are not provided, we infer based on common knowledge that PQLI includes literacy, infant mortality, and life expectancy at age one. Any option not representing these is incorrect.

## Clinical Pearl / High-Yield Fact
A key point to remember is that PQLI is an older index and has been somewhat superseded by more comprehensive indices like the Human Development Index (HDI), which also considers GDP per capita. However, PQLI remains relevant for its simplicity and focus on basic quality of life indicators.

## Correct Answer: D.