The function g(x) = x2 is transformed to obtain function h: h(x) = g(x) + 1. Which statement describes how the graph of h is different from the graph of g? A. The graph of h is the graph of g horizontally shifted left 1 unit. B. The graph of h is the graph of g horizontally shifted right 1 unit. C. The graph of h is the graph of g vertically shifted down 1 unit. D. The graph of h is the graph of g vertically shifted up 1 unit.