Final answer:
In a scientific investigation, the scientific method is the process followed, which includes observation, hypothesis formation, testing, and conclusion.
Step-by-step explanation:
The process used in a scientific investigation that generally follows a set of steps is the scientific method. This method involves a cycle of making observations, asking questions, forming hypotheses, testing hypotheses, drawing conclusions, and communicating results. While inductive reasoning uses particular results to produce general scientific principles, and deductive reasoning predicts results by applying general principles, it is the scientific method that provides the framework for conducting scientific research in a systematic and organized way.