Answer:
Phase II
Step-by-step explanation:
The above question exposes an example of scientific study. This type of study is characterized as a set of basic rules used in the development of an investigation in order to produce scientific knowledge, obtaining the most reliable results possible, either in the production of new knowledge, as well as in the correction and integration of scientific knowledge.
This type of study encompasses some phases, such as observation, hypothesis formulation, experimentation, interpretation of results, and finally conclusion. In the case of the study shown above, the step outlined in the question is phase II, also known as "hypothesis formulation". Phase II begins shortly after phase I, called observation. Observations must be made precisely and very carefully, down to the last detail.
Phase II is a possible explanation for a given phenomenon and should be tested by a large number of experiments. If the hypothesis is confirmed, it may give rise to laws and theories. In this case, we can confirm that "the randomized controlled trial of a postoperative pain control versus aspirin drug that will record 45 subjects in each arm" is an example of hypothesis testing, so this study refers to phase II.