During diffusion the molecules move in constant random motion. <span>The </span>net movement<span> of a substance from a region where it has a higher concentration to a region where it has a lower concentration, due to random molecular motion, is called </span>diffusion<span>. Diffusion is a widespread and important process which occurs in both living and non-living systems. </span>
A systolic pressure of 112mmhg is a representation of the pressure in arteries during the contraction of the ventricles in the heart. So, C is correct. Systole means contraction while diastole means rest.
