Which label belongs in the area marked Z?

Seed plants that lived during the carboniferous impact life on earth today because a. they are the ancestors of all plant life on earth. b. their remains formed coal, which is an important resource. c. they produced fossils that are used to date many geologic events. d. their presence caused oxygen levels to drop, allowing animals to evolve.

Where does the availability of water pose the greatest problem

The african continent is home of the worlds largest desert and longest river . t or f