Unlike cyclopentadiene, 1,3 cyclohexadiene can be stored for long periods at room temperature. When 1,3 cyclohexadiene is heated at 180 degrees C for two hours, a 30% yield of two products A and B, each of empirical formula C12H6 can be isolated. Hydrogenation of either A or B gives the same hydrocarbon C, of empirical formula C12H20. What are structures A, B, & C?