Quaking Aspen (Populus tremuloides) reproduce via rhizomes, creating immense colonies that may include thousands of trees. One colony in Utah, nicknamed Pando, consists of a grove of ~47,000 trunks. Despite their massive size, scientists worry that these stands are vulnerable–why?

These strands are clones, however, due to their low genetic variability, the population becomes susceptible to diseases taking place in plants. Pando comprises grove of about 47000 trunks, these all are genetically similar that develops from a solitary underground species, Quaking aspen tree. Pando is an extremely large clone.  

However, for the past some years, scientists are worried about Pando's health. For the past thousands of years, Pando was living in fine tune with the native wildlife population, but for the past some years, a shift in balance is noticed. As in the absence of the development of novel stems, nothing will be able to substitute the natural withering of the older ones, if this goes on, the death of Pando will take place.  

i think a) betsy can donate only blood to mark is correct because, mark and betsy have the same blood type. whereas nobody else has b+ blood so betsy can't donate to them.

its temperature is increasing. this causes molecular vibrations to increase.