The dependency ratio refers to:

Correct Option: Ratio of dependent population to working population

Explanation:

The dependency ratio is a demographic measure that compares the portion of a population that is typically not in the labor force (dependents) to the portion that is in the labor force (working-age population).

1. Dependent Population: This group generally consists of individuals who are under 15 years of age (children) and those who are 65 years of age and older (elderly), as they usually rely on others for economic support.

2. Working Population: This group typically includes individuals aged 15 to 64 who are economically active and support the dependent demographic through production, income, and taxes.

Mathematically, the dependency ratio is expressed as:

$\text{Dependency Ratio}=\frac{\text{Number of Dependents (Aged 0–14 + Aged 65+)}}{\text{Working-Age Population (Aged 15–64)}}\times 100$

A higher dependency ratio indicates that the working population faces a greater financial burden in supporting the dependent population, which can impact public services, healthcare, and pension systems.