Scientists will continue to investigate the mystery of the yawn. Is it a leftover behavior from before humans had language? Was it a "Hey, I'm sleepy. Let's go to sleep" message? Or is it really just a way to keep our brains cool? While this behavior still is largely a mystery, one thing is certain: you are probably fighting the urge to yawn right about now. Which line shows the main idea of the bolded paragraph? (5 points)

Group of answer choices

Scientists will continue to investigate the mystery of the yawn

A leftover behavior from before humans had language

Was it a "Hey, I'm sleepy. Let's go to sleep" message?

You are probably fighting the urge to yawn right about now