When a person has not taken in suffi cient water they become dehydrated. this may cause a loss of blood pressure, which will trigger the release of antidiuretic hormone (adh) from the hypothalamus and pituitary glands. this hormone signals the kidney to allow reabsorption of water by the blood vessels to bring the blood pressure back to normal conditions.

"a.) well–developed vascular system."

igneous rocks are formed by solidification of cooled magma (molten rock), with or without crystallization, either below the surface as intrusive (plutonic) rocks or on the surface as extrusive (volcanic) rocks.  

the composition depends on the source magma. there are almost a thousand types of composition found till now.  

hope this