Drag a single field "A" to Rows, then drag field "B" to the y axis (vertical). You should see a double ruler appear. This will allow you to view more than one measure on the same chart.
And I see you can also drag field "C", to the y-axis and the line graph for 'C' will also show up on one chart!
To make sure, click the 'Show Me' button and click the chart called 'line (discreet)' which is the 2nd column and 4th chart down.