Correct

摸不着头脑

/ mōbuzháo tóunǎo / 
Strokes

Definition

to be unable to make any sense of the matter/to be at a loss

Example

Definition

be unable to make head or tail of sth; be totally at a loss; be bewildered

1
Zhè
这
jiàn
件
shì
事
wǒ
我
mōbuzháotóunǎo
摸不着头脑
  
。

I cannot make head or tail of this matter.