Question

Which sentence does not contain any punctuation errors?

A.
That striped shirt, by the way fits perfectly.

B.
That striped shirt, by the way, fits perfectly.

C.
That striped shirt by the way fits perfectly.

D.
That striped shirt by the way, fits perfectly.

Answer 1

I guess D

Answer 2

It's B. 'by the way' is a subordinate clause.
As a side note, I don't think this is the right place to be asking grammar questions, maybe try the English section of the site? http://openstudy.com/study#/groups/English

Answer 3

b