Most environments have many niches. If a niche is "empty" (no organisms are occupying it), new species are likely to evolve to occupy it. This happens by the process of natural selection. By natural selection, the nature of the species gradually changes to become adapted to the niche.
Force is a vector quantity so pulling from opposite side will be negative so 750+(-500)= 250N C is the right answer becauseause the man on the right applies greater force.
