The triplets Adam, Jan and Stas and their sister Marysia who is four years older than them were $24$ years old together three years ago. How old is Marysia today? (2001 Math Kangaroo Problem, Level 5-6, Question \#18) 
选项为:A:$$5$$  B:$$8$$  C:$$9$$  D:$$12$$  E:$$15$$  请回答其中一个选项.