Science mysteries: why do people yawn? based on the text, the idea of “contagious yawning” shows that a yawning is a way to keep our brains cool b yawning forces blood down from the brain c yawning keeps us healthy d yawning is a form of communication

the answer is most probably b

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Option D. Based on the text "Science mysteries: why do people yawn?", the idea of "contagious yawning" shows that yawning is a form of communication.

Explanation:

The text firsts explains how scientists have found that the act of yawning helps to keep our brains's temperature cool, allowing it to work more efficiently. Then it goes to explore the concept of "contagious yawning" and it describes it as a type of behavior that intends to send a social message by yawning after someone else has yawned. Scientists believe that maybe we yawn after someone else has in order to show empathy.