Which line from the text shows why scientists continue to study yawning?

one thing is certain: you are probably fighting the urge to yawn right about now.
other scientists believe, however, that yawning is a form of communication.
one mystery that still remains unsolved is why we yawn—what makes us yawn and what purpose it serves.
the theory is that yawning cool the brain, allowing it to work more efficiently.

What are tissues? a groups of tissues that work together b basic units of structure and function c groups of cells that perform the same function d multiple organs that perform a major function

Which of the following statements is most likely correct about a rock belonging to the jurassic age and a rock belonging to the cambrian age? options: 1) they have identical fossils of organisms that have evolved over time. 2) both have animal fossils preserved in them due to weathering and erosion. 3) they contain different fossils because life on earth has changed through time. 4) the fossils in them were formed on the surface of earth due to exposure to sunlight.

Which of the following is a testable hypotheses?