Aseries of closed contour lines most likely represents a
a. valley
b. plain
c. cliff
d. hill

The answer is C. Cliff this is because contoir lines are closer together they represent a steep elevation.

A series of closed contour lines most likely represents a cliff.

Ithink its convection.hope this plz give brainliest!

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.