A hypothesis is which of the following?

• A. A proven fact
• B. A tentative, testable explanation or educated guess
• C. A long-held belief
• D. An untestable claim

Answer: (B)

A hypothesis is a tentative, testable explanation or educated guess about something you want to understand. It starts from observations and knowledge and makes a specific prediction that you can check with experiments or data. It’s not a proven fact; a hypothesis is the starting point for investigation, something that can be supported or refuted by evidence. It’s also not an untestable claim or a long-held belief, because those either can’t be evaluated with data or aren’t necessarily based on testable predictions. A good hypothesis is testable and falsifiable—for example, “If a plant receives more sunlight, then it will grow taller than plants with less sunlight”—and you can measure light exposure and growth to see if the prediction holds. As evidence accumulates, the hypothesis can be revised or strengthened, and it helps build toward a broader theory.