What makes scientists think that arctic areas were once warm? they found wooly mammoths there
O they found fossils of horses there
they found fossils of coral there
O the different layers of snow and ice

well the ice preserves the wooly mammoths

Explanation:its not just snow its bacteria witch means that once living to frozen thats how they know how it looks like and to see what animal its related to now day it related to the elephants

i believe it is-

d.) gravity pulled particles of dust and gas together to form planets.

it can be observed without changing the identity of the object.

it depends on what substance you're talking about as well as many other factors. in quantum mechanics, the observation of particles affects the observers ability to measure certain properties. for example: you can know the velocity of a particle, but you can't know it's position; or you can know it's position, but not it's velocity. it's like trying to find out where a grain of sand is by throwing other grains of sand at it. once you find out where it is, it's been moved. it's also like trying to find an answer to the question of whether or not a tree falling in a forest makes a sound if nobody is there to hear it. paradoxically, the only way to find out is to be there and hear it.