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.
Answer:
The answer is b. The chairman of the board, Bill Smith, will open the conference.
Explanation:
Answer:
Overnight in a state park
Answer: Twinkies are the most delicious snack imaginable.
Explanation:
the answer is transfer appeal