Question

heres an experiment to try: see if you can make your friends yawn by pretending to yawn. just open your mouth really wide, stretch your arms, and inhale. now tell your friends not to yawn. can they do it? probably not! what does that prove? scientists are trying to find out why yawning is so contagious, and how to stop a yawn from spreading. their research may give us information on how the brain works. why does the author say yawning is contagious? people pretend to yawn with their friends. people yawn after seeing others yawn. people stretch and yawn at the same time. people like to do research on yawns.

Explanation:

To determine why the author says yawning is contagious, we analyze each option:

• "People pretend to yawn with their friends" is incorrect as the experiment is about making friends yawn by pretending, not pretending together.
• "People yawn after seeing others yawn" matches the idea of contagious yawning (one yawns after seeing another yawn, like in the experiment where pretending to yawn can make friends yawn).
• "People stretch and yawn at the same time" is about the action during yawning, not why it's contagious.
• "People like to do research on yawns" is about research interest, not the reason for contagiousness.

Answer:

B. People yawn after seeing others yawn.