Final answer:
If reproduction occurs early in the life cycle, the population growth rate increases.
Step-by-step explanation:
If reproduction occurs early in the life cycle, the population growth rate increases. Early reproduction allows organisms to have more offspring, which leads to a higher rate of population growth. This can be seen in species with short generation times, like bacteria, that reproduce quickly and produce many offspring.
On the other hand, if reproduction occurs later in the life cycle, the generation time increases. Organisms that have delayed reproduction invest more time and energy into growth and development before reproducing, resulting in a longer generation time.
Therefore, the correct answer is option b, the population growth rate increases, when reproduction occurs early in the life cycle.