The most accurate statement regarding a population of plants changing over time would likely be:
The plants probably reproduced by sexual reproduction.
This is because sexual reproduction allows for genetic variation within the population, which is essential for evolution and adaptation over time. Asexual reproduction, while it can lead to population growth, often results in less genetic diversity. While some plants can reproduce through vegetative reproduction or asexual means, the presence of genetic changes in a population is typically indicative of sexual reproduction.