Which is the best example of a question that could be used to develop a testable hypothesis?

A testable hypothesis asks about a relationship that can be investigated with measurable results. Plant growth can be measured, and water can be filtered or left unfiltered, so the question about unfiltered water and plant growth can be tested in an experiment. The other questions are less specific or rely on subjective judgments, such as deciding what tastes best or measuring emotion.

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