The digestive system enlists the aid of the cardiovascular system and the nervous system. Blood vessels of the digestive system widen to transport more blood.
The sodium ion content of the extracellular fluid
Quantitative analytic methods refer to methods used in analytical chemistry in order to determine the concentration or the moles of a certain substance in solutions. This includes finiding correct units. The most appropriate answer is a quantitative variable and this is the first choice; Quantitative analytic methods can help you determine or estimate the amount of poison in the blood (solvent).
think its the second one,have a nice day