7. In the diagram below, indicate the order in which these sedimentary rocks accumulated: (note: this sequence is shown horizontally, so you have to rotate the page to put them in vertical succession) (a) D, A, E, G, B, F (b) B, F, G, A, E, D (c) B, F, G, E, A, D (d) D, A, E, G, F, B.