How do we know how animals like snakes and whales looked in the past?

Because they have fossils of the back in the past and you can still see them now

Fossils and bone because of people called paleontologist

By water evaporation from the leaves is created a negative pressure at the top of the tree that promotes the ascension  of the water through channels that are called xylem. there are also two molecule forces that are involved: the intra-water molecules cohesion (water molecules stick to each other) and the adhesion when the water molecules stick to the channels they are running in. this is what enables water to go from the roots to the top of a tall tree.

Your answer is going to be b.