. Diffusion occurs because A molecules constantly move and collide with each other.
B the concentration of a solution is never the same throughout a solution.
C the concentration of a solution is always the same throughout a solution. D molecules never move or collide with each other.

primary succession begins with a bare rock and ends with a forest secondary succession begins after a natural disaster where there is a temporary setback after a forest fire or local destruction, but the surrounding area can fill in

answer: the answer is b

blue stars have the highest surface temp

stellar distances are usually expressed in light-years

the measure of a star's brightness is called magnitude

hope this !

since there are no options posted i'll give you a few examples.

a dolphin's flipper, bird's wing, cat's leg.