Question

why are yawns contagious? we asked a scientist by teresa carey
why are yawns contagious? we asked a scientist
the average adult yawns 20 times per day. and when you feel a yawn coming on, it can be nearly impossible to suppress but why does being around other yawners make you yawn?
pbs newshour asked a speech scientist, a sleep neurologist, a neuroethicist and a neuroscientist who studies brain circuits related to itching why yawns are contagious.
they said the evolutionary value of collective yawning remains unknown, but may have something to do with the desire of an animal to protect the members of its tribe.
there is no scientific consensus on why we yawn.
one theory argues that when humans are tired, we stop taking deep breaths, which causes a build - up of carbon dioxide in the body, said douglas parham, a speech scientist at wichita state university. a yawn might be a special kind of respiration, parham said. it builds up oxygen quickly, while expelling carbon dioxide, even more than a deep breath.
which is the most effective way to separate the two sections at the asterisks? (1 point)
by including an infographic of different types of scientists
by using captions to summarize the article
by using bullets to reorganize the first section
by inserting a heading about the topic of the second section

Explanation:

Inserting a heading clearly signals a new - topic transition, effectively separating sections. Other options don't serve as a direct section - separating tool.

Answer:

by inserting a heading about the topic of the second section