The most appropriate answer to why psychologists rely on the scientific method is:
D. To ensure that all data are collected correctly.
The scientific method provides a systematic and organized approach to research, allowing psychologists to formulate hypotheses, collect data, and analyze results in a way that minimizes bias and increases the reliability and validity of their findings. While options A, B, and C may contain elements related to the practice of psychology, they do not capture the primary reason for the reliance on the scientific method as effectively as option D does.