If i were to try to connect the north pole of one magnet to the north pole of another magnet, the two poles would:
a. flip

b. attract

c. repel

d. none of the above

c. Repel

Opposites attract, the same repel

c- cold periods in earth's history during which glaciers covered much of the surface.

explanation:

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.