Answer: d) Scientific theory
Explanation:
Scientific theory is defined as the explanation that is given for any natural world phenomena and event that takes place .This theory contains reliable facts ,evidence and figure to support the explanation after being tested,observed, analyzed and experimentation.
Other options are incorrect because tentative, weakening action and testing and retesting method for knowing about reliability are not the factors that describe natural world with an evidence to explain its occurrence. Thus, the correct option is option(d).