D. Predators
Predators keep populations of other species in check. This was pretty clearly demonstrated in Yellowstone National Park after the wolves were eradicated there. The deer populations increased to the point that the aspen trees nearly disappeared due to the saplings' being eaten by deer. Since the reintroduction of wolves to the park, the aspen trees have begun to flourish once again.
Polymerization would be the answer you're looking for.
The correct answer is A. A burst of speciation
Explanation:
Adaptative radiation is part of evolution and occurs when a single organism or species diversify into a wide range of species (speciation), this process is called "adaptative" because the speciation occurs due to changes in the environment that make challenging survival usually due to the reduction of resources available and therefore organisms change to adapt to new conditions. Additionally, in adaptive radiation, the new organisms share traits with their common ancestor but also have different and unique traits. Considering this, it can be concluded adaptative radiation a burst of speciation.