Question

Which line from the text shows why scientists continue to study yawning?

Answer 1

I'm pretty sure the answer is "One mystery that still remains unsolved is why we yawn—what makes us yawn and what purpose it serves.
The theory is that yawning helps cool the brain, allowing it to work more efficiently," because scientists are trying to prove the theory wrong, and they are trying to figure out why we yawn, as well.

Answer 2

Answer:

-Other scientists believe, however, that yawning is a form of communication.

- The theory is that yawning helps cool the brain, allowing it to work more efficiently.

-One mystery that still remains unsolved is why we yawn — what makes us yawn and what purpose it serves.

Explanation:

-One mystery that still remains unsolved is why we yawn — what makes us yawn and what purpose it serves:These lines show the gaps in yawning research

-Other scientists believe, however, that yawning is a form of communication. and - The theory is that yawning helps cool the brain, allowing it to work more efficiently:  These lines allow to see there are still several opinions of scientists about yawning reason why the quality of scientists continue to study to verify theories.