Correct Option: A

According to census of India, Age-sex structure is one of the most important characteristics of population composition. Almost all population characteristics vary significantly with age. Age statistics form an important component of population analysis, as most of the analysis is based on age-sex structure of the population. The usefulness of age data is more noticeable when it is cross classified by variables like marital stat us, liter acy educational attainment, economic activity which vary with age in different patterns.