2 graphs. Graph A: a dotted line goes from (1, 0) to (1, 0.25), is solid and horizontal to (2, 0.25), is dotted to (2, negative 0.1875), is solid and horizontal to (6, negative 0.1875), and then is dotted to (6, 0). Graph B. A line goes from (negative 5, 0) to (negative 3, 0.25), and then decreases to (3, 0). Which statement about the graphs is true?

Graph A is a valid density curve because the part of the graph from 2 to 6 is below the horizontal axis.
Graph A is not a valid density curve because the part of the graph from 1 to 2 is above the horizontal axis.
Graph B is not a valid density curve because part of the horizontal axis has negative values.
Graph B is a valid density curve because the curve is above the horizontal axis, and the area under the curve is 1.