Which statement best describes the earliest ancestors of a plant? a. they had no competition b. they were vascular c. they had seeds d. they lived in water

1. the is the thinnest part of the earth. 2. the is the thickest part of the earth. 3. what metals are mentioned in the text?

When analyzing tree rings, what do scientists assume a thin ring indicates?

Which of these is an example of land degradation? a. containers designed to store pollutants leak. b. fertilizers provide too many nutrients to crops. c. garbage is buried so the land can be reclaimed later. d. a drought kills all the plants in an area, leaving bare land