Answer:
C) Clone the plant
Explanation:
Cloning is the process by which genetically identical offsprings are obtained naturally or artificially. In nature, genetically similar individuals or offsprings are obtained from asexual reproduction.
If a horticulturist succeeds in having a single plant with the desired trait than to establish a line of such plant she should clone the plant so that the plants which are obtained after cloning have the same traits which were present in the parent plant. Therefore the correct answer is C.