What is an indication of positive population growth under normal conditions?

An increase in the number of young individuals

The correct option is (b) An increase in the number of young individuals.

Positive population growth is indicated by a larger number of young individuals in a population. This suggests that the birth rate is higher than the death rate, leading to an overall increase in population size. Young individuals represent new additions to the population and contribute to its growth. As they mature and reach reproductive age, they have the potential to produce offspring and further contribute to population growth. Therefore, a larger number of young individuals is an indication of a thriving and expanding population.

The other options are not correct. Option (a), less number of young individuals, indicates a population that is declining. Option (c), large number of old individuals, indicates a population that is stable or declining. Option (d), large number of childbirth, is not a specific enough answer. It is possible to have a large number of childbirths in a population that is not growing rapidly.

So, the answer is (b) large number of young individuals.