i'm going to play basketball after school.what about you?

i'm going to play basketball after school.what about you?
-i'm going to play basketball after school.what about you?
-_________.
选项有：
A yes,basketball is popular.
B are you?it's so hot.
C i like basketball very much.
D so am i
应该选谁?
但是标准答案为B，而且题目是往年中考题，我个人认为也是D，倒装表示我也将要去。
看到后两位朋友的回答，so do i 是倒装句型，表达我也如何如何，与前面陈述行为一致；但是do是需要随着前面陈述句的谓语变化而变化的，比如he has finished the work.So have I.此时句型中的do要换成助动词have。陈述句说i'm going to....倒装句用so am i 是没有错误的。所以这个问题我就不是很明白，我觉得首选应该是D，B在语意上也通，但是答案却是B，拜谢！