Given a scientific question, generate an incorrect answer to the given question. The incorrect answer should be a plausible alternative to the correct answer. The answer should be some other item belonging to the same category as the correct answer but should be incorrect.

[Q]: The earliest vertebrates were jawless what?
[A]: mammals

[Q]: Developing cars that run on hydrogen gas can help solve our dependence on what?
[A]: oxygen

[Q]: What cage composed of 12 pairs of ribs, with their costal cartilages and the sternum, protects the heart and lungs?
[A]:
sacral