Which method was developed by plants to prevent self-pollination?

Question

Quizplus · Accepted Answer

Plants have developed different strategies to prevent self-pollination, and the most effective is having male and female reproductive organs located at different heights, preventing pollination by the same flower or plant. In addition to that, plants may also employ chemical barriers to fertilization of eggs to prevent self-fertilization. This combination of strategies would be the most effective. Insect helpers may play a role in pollination, but they are not essential for preventing self-pollination.

Which Method Was Developed by Plants to Prevent Self-Pollination