**Core Concept**
The Physical Quality of Life Index (PQLI) is a composite measure used to assess the overall quality of life in a country. It combines three basic indicators: literacy rate, infant mortality rate, and life expectancy at age one, to provide a comprehensive picture of a nation's well-being.

**Why the Correct Answer is Right**
PQLI is a widely used index that takes into account three essential factors: literacy rate, which reflects the level of education and knowledge among the population; infant mortality rate, which indicates the number of deaths among children under one year of age, often related to access to healthcare and living conditions; and life expectancy at age one, which measures the average number of years a person is expected to live after reaching the age of one, influenced by healthcare, living conditions, and socio-economic factors.

**Why Each Wrong Option is Incorrect**
**Option A:** Literacy is indeed one of the components of PQLI, but the correct answer includes two more factors, making it an incomplete option.

**Option B:** Infant mortality rate is a crucial component of PQLI, but omitting literacy and life expectancy at age one would result in an incomplete index.

**Option C:** Life expectancy at birth is not a direct component of PQLI; instead, life expectancy at age one is used to provide a more accurate picture of a population's overall health.

**Option D:** Income is not a component of PQLI, which focuses on basic indicators of well-being rather than economic factors.

**Clinical Pearl / High-Yield Fact**
PQLI is a useful tool for evaluating the overall quality of life in a country, but it has its limitations, as it does not account for other important factors such as access to education, healthcare, and economic opportunities.

**Correct Answer:** D. Incomed is not included in PQLI; however, the three components included in PQLI are -a) Literacyb) Infant mortalityc) Life expectancy at age one.