In the graph, a sample of water is heated from 40 degrees celsius to 100 degrees celsius. which statement correctly describes the curve? a) qr- liquid only rs- phase change liquid-gas st- gas only b) qr- liquid only rs- phase change liquid-solid st- solid only c) qr- solid only rs- phase change solid-liquid st- liquid only d) qr- phase change solid-liquid rs- liquid only st- phase change liquid-gas