Which statement best explains the $80/20$ rule $($also called the Pareto Principle$)?$

that $80\%$ of consequences come from $20\%$ of the causes, asserting an unequal relationship between inputs and outputs.

that in business $80\%$ of a company's revenues come from $20\%$ of the customers.

that $20\%$ of consequences come from $80\%$ of the causes, asserting an unequal relationship between inputs and outputs.

both $"$a$"$ and $"$b$"$ are correct.