Which of the following statements about secondary succession is true?
a. secondary succession occurs in ecosystems that have no vegetation.
b. secondary succession affects ecosystems that are already established.
c. ecosystems require pioneer species to undergo secondary succession.
d. secondary succession can occur in areas without soil.

Option B,  Secondary succession affects ecosystems that are already established, is the right answer.

Explanation:

There are two types of ecological succession (the primary and the Secondary succession) in the life of a plant. Here, the secondary succession is a process which starts with an event such as a hurricane, forest fire or harvesting etc. which causes a reduction in an already organised ecosystem. Therefore, in the given options, option b, is correct.

for e2020. the answer would be some directions from the mountain range so we can find mt. whitney. to locate which direction is north, you should use a   compass. this would not only find mt. whitney, but also becuase of this long paragraph you would get points because it's not like anyone actually reads your work becuase once they read the first sentence it sounds dumb enough to not read becuase i'm not good at answering this but the answer is compass for your benefit.

for e2020 ; -;

show options, then i will gladly answer you question.

have a good day.