Identify wrong pair of statements.
I) During plant succession, some species colonise an area and populations become more numerous, whereas populations of or species decline and even disappear.
II) Both hydrarch and xerarch successions lead to mesic conditions.
III) Secondary succession is a slow process when compared to primary succession.
IV) In successive seral stages, re is no change in diversity of species of organisms.

During succession, the area is colonized by some pioneer species and then are eliminated by successive colonizers.Hydrarch(starts in water) and xerarch(start in a dry area) and both after few series progress to the mesic condition.Secondary succession is a process started by an event, like a forest fire or harvesting or hurricane and is relatively faster, when compared to primary succession. During succession, the individual transitional communities are termed seral stages or seral communities. In the successive seral stages, there is a change in the diversity of species of organisms, increase in the number of species and organisms as well as an increase in the total biomass.
Thus, the correct answer is option C.