Based on the scenario provided, the best explanations that match the description are:
A. The new root growth is a result of mitosis.
B. The new plant formed from asexual reproduction.
D. The new plant is genetically identical to the original plant.
These options accurately reflect the process involving a cutting, where the new plant grows from the original plant through asexual reproduction, resulting in new root growth through mitosis and producing a genetically identical plant.