Mary simplified the math expression below. The steps that she took are shown. Which is the line where Mary first made her mistake. Line A: – 6 + 9 Line B: [8 + 5 x 3] – 6 + 9 Line C: – 6 + 9 Line D: 23 – 6 + 9 Line E: 23 – 15 Line F: 8