Raynaud's disease results in brief periods of vasospasms. this disease affects blood supply to fingers and toes. it is also known to affect blood flow to lips, ears, nose and nipples. during what is called as "raynaud's attacks", the skin may turn white and then blue for a short time. which of these best describes why these symptoms occur?

What is point source pollution of an aquatic ecosystem? a) pollution of freshwater sources b) pollution from many sources that combine into one c) pollution that occurs over a wide area; water that runs off from fields, parking lots, and other land surfaces d) pollution that can easily be identified with a single discharge source, such as an open pipe which drains into a body of water