In which layer of the earth does the tempature vary a. inner core b. outer core c. mantle d. crust

Migration people get up and go cause they feel it is best for them 

Except common history

Answer( solar wind );

When a lake, river or other aquatic  system  becomes  eutrophic, it can have serious negative effects on other organisms like fish, birds and even people.if an algal bloom is so bad that it causes wide-spread death  in  the  water, the organisms that die will all sink to the bottom and start to decompose.