Answer:
They test or measure something.
Explanation:
Primary research articles report on research that has been completed. Therefore, a primary research article will review and analyze studies, and will state the research question and hypotheses of the studies presented. A primary research article does not test or measure anything, but will report on studies that do.
The photoreceptors would be your eyes, chemoreceptors skin, olfactory for nose and mechanoreceptors for obviously tongue hope this helps.
