Choose the best answer 1.His youngest son, [ C ] is now working at the Chinese Academy of Science. A.that is twenty-five B,who is twenty-five age C.who is twenty-five D.whose age is twenty-five years old Right C I choose D 2.You may depend upon it [ D ] your son will be taken good care of here. A.when B,which C,how D,that Right D I choose BEh, I want to know why I should choose D, not another answer.