The correct option is A Cauliflower
Cauliflower has the compound corymb structure, in which the peduncle is branched in a corymb (racemose inflorescence in which all flowers lie at the same level) manner and each branch in turn bears flowers in corymb manner.
Gulmohar has a typical raceme, mustard has corymbose raceme (upper flowers in a raceme are arranged like a corymb), and sunflower has a capitulum (the peduncle forms a flattened receptacle that bears sessile flowers called florets).