What did Charles Darwin learn from reading the work of geologists in the early 1800's?
A. All geological change is caused by living organisms.
B. Earth is relatively young.
C. The processes that formed old rocks on Earth do not operate today.
D. Earth is very old.

digestion

it excretes wastes

the answer is true when observing or determining population size, a direct observation is use, in which each organism is counted in a population or in an area. one benefit of this measure is that you get the exact population count but it will take a long time to  determine  the  size  of a  population.

the answer is d. none of the above

the earth is thought to have been formed about 4.6 billion years ago by collisions from a cloud of hydrogen, helium, rock, ice and other materials. these were pulled together by gravity to form objects in and around earth like- asteroids and small early planets called planetesimals.

so, the best possible answer to this question will be option d- to harden materials to form different parts of earth’s layers