Question

what is the main idea of the article \the science of hydration\?
to promote the 8x8 rule
to introduce new hydration techniques
to discuss the history of hydropathy
to explain the importance of hydration and debunk myths

Explanation:

Without reading the article, we can make an educated - guess. "The Science of Hydration" likely focuses on the scientific aspects of hydration. Promoting the 8x8 rule is too narrow, introducing new techniques may not cover the whole scope, and discussing hydropathy history is off - topic. Explaining the importance of hydration and debunking myths is a comprehensive and likely main idea related to the science of hydration.

Answer:

To explain the importance of hydration and debunk myths