Answer:
I think it is 3.) Creating a summary
It's a boys boarding school.
They show the similarities of all the teachers, and then they show how different Mr. Keatings is compared to them.
<span>Todd is quiet and doesn't want to get involved.
hope this is what your looking for :)</span>
A non-restrictive modifier add information that does not restrict who the subject can refer to (compare to "The one Marlena that enjoys many subjects" -this one restricts the subject to a specific Marlena). Here it's "who enjoys many different subjects" - it adds additional information about her, but doesn't change the referent.
