To label their produce as organic, farmers have to obtain a certificate showing that no ________ chemicals have been used to kill pests on the farm for two years.
【单选题】下列说法正确的是 ( ) A .将蘸有浓氨水和浓硫酸的玻璃棒靠近,会产生白烟 B .将 SO 2 通入盛有品红溶液的试管中,红色褪去,给试管加热无明显变化 C .将干燥的 Cl 2 通入装有红色鲜花的试管中,红花褪色,说明 Cl 2 具有漂白性 D . Cu 和浓硫酸在加热的条件下可以反应,体现浓硫酸的强氧化性和酸性