Answer: The correct answer is "a. reliable and valid".
Explanation: Credible experiments are reliable and valid.
Credible experiments are reliable because reliability is intended to ensure that a researcher, following the same procedures described by another previous researcher and conducting the same study, can reach the same results and conclusions.
And an investigation will have a high level of validity to the extent that its results reflect an image as complete as possible, clear and representative of the reality or situation studied.
