What is a mutation?
a. a change in a gene which is harmful, beneficial, or has no effect at all.
b. a change in a gene which is only harmful.
c. a change in a gene which is only harmful.
d. no change in a gene.

the answer is A hope this helps

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.