use of comma

[kapur.arnav]

This, no doubt, will be a proper place to give some to my antecedents, as well as a few of the details
of the crime for which I was sent to the penitentiary.

A. This, no doubt will be the proper place to give some of my antecedents, as well as a few of the
details of the
B. This, no doubt, will be the proper place to give some of my antecedents, as well as a few of the
details of the
C. This, no doubt, will be the proper place to give some to my antecedents, as well as a few of the
details of the
D. This no doubt, will be the proper place to give some of my antecedents, as well as a few of the
details of a

OA - B... Why do we need comma after no doubt

[Isaac@EconomistGMAT]

Without the comma, the sentence would be awkward and could be interpreted differently because of the placement of 'no doubt' as a kind of modifier (it is like the word surely, definitely, of course, also etc). With the comma the no doubt more strongly refers to the 'placement' of 'this' and not to the 'will be'.

In broad terms, such phrases/words are considered types of 'interruptors' which interrupt the normal flow of the sentence and so usually utilize a comma to clarify matters and make the reading/flow more easily.