下列哪项实例说明植物的不同器官对生长素的敏感性不同
A:植物的向光性
B:顶端优势
C:将植物平放后,根向地生长,茎背地生长
D:除草剂可以除掉田间的双子叶植物
-I will go to the countryside to see my grandmother this afternoon, so I can't go swimming with you.
-___________.