The statement 'Exploring the relationship between the material in a rock sample and its hardness' correctly describes an experimental investigation (Option C).
<h3>What is an experimental investigation?</h3>
An experimental investigation is defined as a procedure used in the scientific method to test an explanation or hypothesis, which can be confirmed or rejected.
In conclusion, the statement 'Exploring the relationship between the material in a rock sample and its hardness' correctly describes an experimental investigation (Option C).
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