Answer: It is A
Explanation: C and D are jokes/ complete lies. B is wrong because Darwin did observe that animals and plants adapted (evolved) to suit their environments.
The organ is the LUNGS.
The lungs excrete carbon dioxide and water vapour through metabolism.
The lungs are used for breathing in humans, through the lungs we take in oxygen which is carried by the blood to all the part of the body and we exhale carbon dioxide which is a waste product generated as a result of the reactions that occur in the body.
Evolution is caused by genetic mutations that become favorable for survival.
For example if a bird has a mutation that gives it a longer beak and it lives in an environment in which a longer beak lets the bird catch more food- the longer beak becomes a favorable trait.
Now the bird is able to survive “better” thus it lives longer(due to its ability to catch more food). Because of this it reproduces more and passes the trait on to its offspring.
Overtime this mutation takes over the population of birds in the area.
The study is called Ecology