Question

drag the missing word into place
scientists performed a(n) blank to study the effects of
daily exercise on dogs.
options (in yellow circular buttons): experiment, conclusion, hypothesis

Explanation:

To determine the correct word, we analyze the context: scientists studying the effects of daily exercise on dogs would perform an "experiment" (a procedure to test effects). A "hypothesis" is a proposed explanation, and a "conclusion" is the result of analysis—neither fit the action of studying effects here.

Answer:

experiment