I WILL GIVE BRAINLIEST Which of the following statements is true?

If a hypothesis is proven false, a mistake has been made in the experiment.

The independent variable is what changes as a result of the dependent variable.

Changes in the independent variable cause changes in the dependent variable.

Once a hypothesis is proven true, it becomes a theory and cannot be disproved.

Engineers find a new metal that is stronger than steel but much lighter. this material is also significantly cheaper than what is currently used for most aircraft, available in large quantities, and easy to manufacture. the engineers are excited because this new material will lower the costs of buying and operating airplanes for companies. what is probably the best step for the engineers to make next?