Final answer:
The greatest proportion of young individuals is found in economically underdeveloped countries due to their higher birth rates and larger percentage of younger populations.
Step-by-step explanation:
The greatest proportion of young individuals can be found in economically underdeveloped countries (option b). This is because these countries typically have higher birth rates and a larger percentage of their population in the younger age groups. In contrast, economically developed countries often have lower birth rates and an older demographic, with a higher proportion of middle-aged and elderly individuals. Age structures of economically undeveloped countries show greater proportions of children and fewer proportions of elderly people, indicating a younger population overall.
It's important to note that as economies develop and urbanize, there is a trend where the population tends to live increasingly in urban areas. This urban shift, however, does not necessarily correlate to a younger population, as economically developed regions still tend to have lower birth rates regardless of urbanization. Thus, the age distribution is distinct from the rural-urban population distribution.