Antonyms are words that have contrasting, or opposite, meanings.
Choice D is correct. Parsimonious means 'miserly' the opposite being extravagant meaning 'lacking restraint in spending money'. For example: The elder son is extravagant while the younger is judicious in spending money. Choice A means 'a strong supported of a party or cause'. Choice C means 'allowed'. Choice C means 'showing'. Choice A, B, and C are wrong.