Final answer:
The net reproductive rate is most directly useful for predicting future population size on a generation time frame.
Step-by-step explanation:
The net reproductive rate is most directly useful for predicting future population size on a generation time frame.
The net reproductive rate, also known as R0, measures the average number of offspring produced per individual in a population over its lifetime.
By calculating the net reproductive rate, scientists can estimate how a population will change over time based on the number of individuals born and surviving in each generation.