Answer:
1 2 and 3
Explanation:
Because it is like a food chain without the bacteria or woms many animals would be out of food.
Fish, reptiles, birds, and mammals have very similar embryos with gill slits and tales, but all but fish get rid of the gills as they mature
Erosion and collisions
such as mountain ranges and conyons
untreated high blood pressure, history of aneurysms in family, arteriovenous malformations (tangles of arteries and veins that disrupt bloodflow, and cigarette useage.
