consider what you have learned about american history during the period of 1860 to the early 1900s. how do the stories in the realism and regionalism unit reflect what was going on in the country then?

i believe the answer is d

. a function is a relation in which each input has only one output. in the relation , y is a function of x, because for each input x (1, 2, 3, or 0), there is only one output y. x is not a function of y, because the input y = 3 has multiple outputs: x = 1 and x = 2.