I need help with these questions I will make you Brainlest please help

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

What do nitrifying bacteria convert

The image below shows a common blood pressure gauge. what does this device do? a. measures the level of oxygen present in the blood b. measures the pressure of blood when the lungs expand and compress c. measures the electrical activity of the heart d. measures the pressure of blood when the heart contracts and relaxes