If I go ———— A.so does he B.so will he

if 引导的条件状语从句
主句一般将来时，从句一般现在时
例子：
If it doesn't rain tomorrow, we'll go hiking.

所以，选B

if 引导的条件状语从句 。从句要用一般式来代替将来时
例如：
he said:if it didn't rain next day, they would go hiking.
he won't go to school if he still has trouble in it!
而这句话后面应该是If I go ，he will go too!再将后句用“so +系动词/情态动词/助动词+人称”的格式表示：“也... ...”就是so will he

所以，选B

B.so will he

B