--sorry,l forgot to post your letter.--Never mind,l____it myself.A.am going to post B.will post

题目

--sorry,l forgot to post your letter.--Never mind,l____it myself.A.am going to post B.will post
C.could post D.will be going to post
AB两个不是一样的么,选哪个,为什么?

答案

b
a的意思是计划做某事,从上下文看,他明显没有打算自己去邮递
b只是表示要去做而已,和a用处不同