19. In Utah of the USA, there is a clone of aspen trees that covers over 100 acres. Such clones can be considered as a single plant with many stems. It appears that the first stem of this clone originated over 80,000 years ago, even before there were humans in North America. What likely contributes most to the long-term survival (long life span) of aspens? (A) If parts of the organism (clone) are damaged, there are still other parts that can continue growing. (B) All parts of the clone carry the same genes. (C) A shared root system means that all stems receive the same nourishment. (D) Sexual reproduction can occur more frequently in clones.