What does the hand with a pointer mean when you put your mouse over the virtual volcano? a.
You are able to continue if you click your mouse.
c.
both of these
b.
You can watch the volcano erupt.
d.
neither of these

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.

the answers would be

the first one and the second one