It is determine by brightness
<span>Erosion by rivers is a main valley-forming
process; other processes, such as movement of the earth's crust and
glaciers, also have an important part in some cases. The rate at which a
river deepens its valley depends on several factors.</span>
I am almost positive that the answer is A. freezing
Answer:B
Explanation:
Red star had a lower temperature than yellow-white therefore it is cooler than yellow-white stars
