The diagram describes the ABC model of flower patterning in Arabidopsis where the A, B and C functions are operational in the whorls (1 + 2), (2 + 3) and (3 + 4), respectively, in the wild-type flower. Removal of A or C function results in the floral organ arrangements as (carpel; stamen; stamen; carpel) or (sepal; petal; petal; sepal), respectively. Based on these observations, which ONE of the following molecular pathways is CORRECT for floral organ pattern generation? Arrow indicates activation and bar indicates inhibition.