Answer: It's an EXPERIMENT
Explanation: Experiment is done when we apply anything to a samples or conditions in other to study another sample or conditions.
Observation is done when, we study samples or conditions in it's natural way, without application of anything that may alter it's result.
Because the researcher has applied fertilizer to one side and did not apply to the other side, that means he has performed an experiment. Since he wasn't observing the two sample in it's natural way without any external application.
This suggestion reflects a concern with causal mechanisms. The Causal mechanism is the procedures or passageways over which an outcome is taken into being. There are two broad types of theories of causation which is the Humean theory which is causation as regularities and the causal-realist theory which is causation as a causal mechanism. The Humean theory embraces that causation is completely established by facts about empirical regularities among noticeable variables in which there is no fundamental causal nature, causal power or causal necessity while the causal-realist takes concepts of causal mechanisms and causal powers as essential, and holds that the undertaking of scientific research is to attain at empirically defensible theories and hypotheses about those causal mechanisms.
Refused allied requests for their surrender
Charles Cooley would say this is A. The looking-glass self
