Final answer:
Sexual reproduction by seeds is the plant propagation method that ensures genetic diversity, in contrast to asexual methods like cuttings, grafting, and micropropagation.
Step-by-step explanation:
The plant propagation process that ensures some genetic diversity is sexual reproduction by seeds. Unlike asexual methods such as cutting, grafting, and micropropagation, seed propagation involves the combination of genetic material from two parent plants, which introduces variation. This variation can be enhanced through the breeding system and can lead to the creation of novel plants. Additionally, hybrid seeds, which are the product of controlled cross-pollination, are a significant aspect of the green revolution, contributing to genetic diversity and crop improvement.