Answer:
The correct answer is: Asexual reproduction.
Step-by-step explanation:
We know that Stephan observed a new plant growing from where a twig cut from rose was planted in the soil. This is an example of asexual reproduction where a new organism carries the characteristics of the parent.
The process of growing a plant from a twig is known as budding where a part of an organism regrows and produces two separate but identical organisms.