Hello. You did not present the cladogram to which the question refers, which makes it impossible for it to be answered. However, I will try to help you in the best possible way.
A cladogram is the representation of the evolutionary relationships between living beings, showing ancestry and the genetic relationship between them. The cladogram is represented by lines and dots. The lines represent the evolutionary time and the dot between them represents the ancestor of a new species. In this case, to answer your first question, we can consider that the most recent ancestor of all species is the ancestor of the central line. However, the most recent ancestor, shared only by gymnosperms and angiosperms, is the one that is in the dot closest to the lines that represent gymnosperms and angiosperms.
