In circumstances in which the word that is used to begin an essential modifier and in which there is no unusual reason to use a comma before the word that, there is no good reason to put a comma before the that.
At the same time, making a habit of ruling out answer choices merely because they contain commas before the word that is not the way to go, as there are situations in which placing a comma before that is appropriate.
Here's one.
He believed, without having any real reason for doing so, that his dog would return shortly.
In that sentence, the presence of a parenthetical phrase before that means that placing a comma before that totally makes sense.
Here's an example of a comma appropriately placed before a restrictive modifier.
The car, a jalopy, that ran over my pizza was later found in Tom's driveway.
Here's another example of an appropriate comma before that.
His conclusion, that he would succeed in building a flying car, was the basis for his decision to quit his day job.
Once again commas set off part of the sentence, and, of all things, that part begins with that.
Gee, there's even a comma between things and that in my explanation.
So there are situations in which it makes sense to put a comma before that, and so, as is usually the case, blindly following a rule is not the way to GMAT SC success. That this is the case makes sense, because the GMAT is an entrance exam for business school, and blindly following rules is not a skill required for business school success. Rather, doing well in GMAT SC, in business school, and in business itself, requires using nuanced approaches involving observing and analyzing what is going on in situations and evaluating the effectiveness of how things are being done.
