Which event in Earth’s history most directly allowed life to exist on land? Earth’s temperatures increased, causing widespread evaporation. Earth collided with a large object, forming the moon. Single-celled organisms released oxygen into the air when they photosynthesized. Single-celled organisms absorbed harmful gases from the air when they first formed.

c: Single-celled organisms released oxygen into the air when they photosynthesized.

Explanation:

got it right on edge. also if there were no oxygen animals and humans could not live

events in order:

1.       vishnu schist

2. zoroaster granite

3. bass limestone

4. hakatar   shale

5. igneous intrusion

6. shinumo quartzite

7. dox sandstone

8. tapeats limestone

9. bright angel shale

10. muav limestone

11. temple butte limestone

12. redwall limestone  

nonconformity

answer: the unkar group shows angular unconformity because the layers are turned at angle.

unconformity

answer: specifically the angular unconformity occurs between the cambrian and precambrian rocks. the dox sandstone, shinumo quartzite, hakatar shale, and bass limestone have been filled. an angular unconformity occurs between the cambrian and precambrian rocks. the dox sandstone, shinumo quartzite, hakatar shale, and bass limestone have been filled.

disconformity

answer: the disconformities aremarked irregular lines between the sedimentaryrocks layers.

i think the answer is a.keratin is the pigment responsible for skin color.