Final answer:
In a country with more young children than teenagers, and more teenagers than adults, the population is likely to grow, indicating that it will increase in 30 years. The correct option is b.
Step-by-step explanation:
If a country like India has a larger number of young children compared to teenagers, and more teenagers than adults, this signifies a demographic profile of a population that is likely to experience growth in the future. Given this age structure, the population will increase in 30 years (option B). The age distribution pattern of having more young individuals at the base of the pyramid is characteristic of underdeveloped countries where birth rates are high and a significant portion of the population is of reproductive age or approaching it, which leads to rapid population growth. As these younger children and teenagers grow into adulthood, they will contribute to the next generation, sustaining the population size or potentially increasing it. Therefore, the country's population is not stable but on an upward growth trajectory, which is consistent with the patterns observed in less economically developed countries with high birth rates and lower life expectancy.