Why did most European powers use indirect rule to control their colonies?

Which of these belongs to the united states after the spanish american war ?

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.

Look at the graph. where p is price and q is quantity, what might cause a move from b to a?