Land plants evolved long before any animals appeared on Earth. When they came onto land, they needed ways to keep from losing water, to reach the sun, and to produce oxygen. They started to convert the atmosphere from carbon dioxide to oxygen. Which of these is believed to be the common ancestor of land plants? A. oak trees, because they are the dominant species in many areas
B. rose bushes, because they produce a sweet-smelling aroma
C. grass, because there is so much of it found on the land
D. green algae, because they use the same photosynthetic pigments as land plants