Primary succession starts with bare rock which is broken down by either lichen or moss to make soil while secondary succession starts with developed soil
It was used till the 1960s. Hope i helped.
Answer:
B. Is what the scientists manipulate in the experiment.
Explanation:
The Independent variable is not dependent, or doesn't rely, on another variable in the experiment. So, it would make the most sense that they would manipulate the Independent so that they can watch and see how the dependent variable reacts to the manipulation, or the change, in the independent variable.
Probability = number of possible outcomes / total number of outcomes