Roof valleys came from from from threes in earths crust white in the valleys were slowly move at a rate of only a few millimeters a year which of these best describes the best type of tectonic activity that forms rift valleys

bc blah

explanation:

bc blah

the real answer is b. scintillation counter

b a mature ovary of a plant.

only about ten percent of the energy at one trophic level is passed on to organisms at the next trophic level. the remainder of the energy is used in life processes or lost as heat.