（）Mrs.king kept weighing herself to see how much— she was ge

选择A
解析：the heaviest 意思为：最重的,不符合句意.
the heavier 意思为：更重的,此处用比较级表示与过去比较,意思符合.
Mrs.king kept weighing herself to see how much the heavier she was getting.
翻译为：King女士不停地在称重看她（与过去相比）重了多少.
对你有所帮助的话,