To be scientifically valid, a hypothesis must be

• A. Testable and falsifiable.
• B. Based on belief.
• C. A proven fact.
• D. Irrefutable.

Answer: (A)

In science, a hypothesis must be testable and falsifiable. Testable means you can design observations or experiments that would show whether the claim is true or false. Falsifiable means there exists a possible outcome that would prove the claim false. This combination lets science make predictions and be open to revision when new data emerge. For example, if you hypothesize that a certain fertilizer makes plants grow taller, you can test this by comparing treated and untreated plants and measuring their growth. If some treated plants don’t grow taller, or untreated plants grow more, the hypothesis can be contradicted and refined. Statements based on belief or that claim a fact is proven beyond doubt aren’t scientifically valid because they aren’t open to testing or falsification. In science, even well-supported ideas aren’t declared proven with absolute certainty; they’re supported by evidence and can be revised with new data. Likewise, a claim that cannot be tested or disproven isn’t something science can evaluate.