Regions in the milky way where density waves have caused gas clouds to crash into each other are called clumps.Clumps are molecular clouds (interstellar clouds) with higher density,where lots of dust and gs cores resides. These clouds are the beginning of stars.
Answer: I would say the answer is B.
Explanation: It looks and sounds the most correct.
You don't count trailing zeros. A.29.3
The importance of having a control group is to see how much your other test subjects changed. You use the control to compare.