Answer:
C. Successive generations of plants adapted to each new niche.
Step-by-step explanation:
The process by which species with diverse ecological and morphological variations specialized for various niches arise from a common ancestor is known as adaptive radiation.
Due to variety in habitat and diet, species diversify in order to fill the various niches within the same environment. For example, in the Finches observed by Darwin in the Galapagos islands, adaptive radiation is seen in how their beaks have changed in size and structure so that they now became adapted to different diets. Some species eat mostly animals such as insects, whereas others became adapted to feeding on seeds or plants.
In the case of the plants, adaptive radiation would also play a role in how the species diversified to fill each new niche.