Consider the study design and summary data presented in Exercise 12.2.7 to examine the relationship between fungus

Question:

Consider the study design and summary data presented in Exercise 12.2.7 to examine the relationship between fungus growth and latisaric acid concentration.
(a) Is this study an observational study or an experiment?
(b) It is suggested that acid could be used to retard fungus growth. Could these data be used to verify this claim? If not, what could be said? Briefly explain.