Final answer:
The correct answer is 'a) Hypothesis,' which is a tentative and testable statement about the relationship between two or more variables or individuals that can be investigated empirically.
Step-by-step explanation:
A hypothesis is a tentative and testable statement (prediction) about the relationship between two or more variables or individuals. It is a proposed explanation for observations or phenomena that is sufficiently precise to allow for systematic investigation. In certain contexts, such as sociology, a hypothesis may predict how one form of human behavior could potentially influence another.
For instance, the hypothesis could state that 'If a person tries a new studying strategy, then their test scores will improve', which is directly testable and can be supported or refuted by gathering and analyzing relevant data.