Which of the following activities are part of scientific investigations? OA. comparing and contrasting
OB. communicating
OC. observing
OD. all of these

What protects the lining of the stomach from acidic gastric juices?

Which best describes red blood cells? a. they are colorless b. they protect against disease-carrying microorganisms c. they transport oxygen throughout the body d. they aid in blood clotting

Other than earth, is also known to have magnetic pole reversal? a: venus b: mars c: earths moon d: the sun