Question

what must always be present in order to form a true scientific explanation? a empirical evidence b controlled variables c subjective evidence d dependent variables

Explanation:

A true scientific explanation must be based on evidence that can be observed, measured, and verified. Empirical evidence meets this criterion. Controlled variables (B) are used in experiments but not always required for a scientific explanation. Subjective evidence (C) is based on personal feelings or opinions, which is not scientific. Dependent variables (D) are part of experimental set - ups, not a core requirement for a scientific explanation.

Answer:

A. empirical evidence