Question

select the word that means easily spread to others. when one person yawns, chances are that the people around that person will yawn also, in fact, almost half of adults yawn when they see someone else yawn. even though many people experience this, scientists dont know why yawning is contagious.

Explanation:

The key - word "easily spread to others" is defined by the word "contagious" in the text which describes yawning behavior.

Answer:

contagious