How has Charles Darwin contributed to the study of evolution? A.
He proposed the theory of natural selection.
B.
He excavated and studied fossils.
C.
He was the first one to use a 3-D printer.
D.
He proposed the genetic relationship between species.

acid rain does not usually kill trees directly. instead, it is more likely to weaken the trees by damaging their leaves, limiting the nutrients available to them, or poisoning them with toxic substances slowly released from the soil. the main atmospheric pollutants that affect trees are nitrates and sulphates.