During the second industrial revolution, which building material became one of the most important in the world?

7. how did the early egyptians use the flooding of the nile river to their advantage? they diverted the water to flood their enemy's lands and destroy their crops. they created an easier way to travel to the mediterranean sea and the indian ocean. they established a new water-based athletic event for the ancient olympics in greece. they devised an innovative irrigation system, which created a surplus of food.

Which events are correlated but do not necessarily have a causal relationship?

If a question is possible to study, that means it is a) focused. b) relevant. c) feasible. d) factual.