Answer:
waterway has its own particular characteristics related to water flow, velocity, and quantity.
Altered water ways or hydrology defines the variation in such characteristics including water flow. Water flow naturally depends on the climate and landscape ( valleys, mountains and flood plains).
There are several examples of people changing the way water flows such as construction of a dam or weir and the addition of a culvert or pipe. Dams are use to control the flow of water and through culvert or pipe, the flow or direction can be changed.
Changes in vegetation and landscape by people also affects the flow of water as well.
They are measuring the time that two species have been evolving independently.
A molecular clock is a method that is used by scientists to estimate the time that two species evolve separately using the knowledge of the DNA differences. To carry out this method, scientists use (i) an estimate of the number of genetic mutations that occur between two closely related species and (ii) the average genetic mutation rate to estimate the time in prehistory when the two species split.
B. the test tube
C. the x-ray machine
D. the light microscope