Which sentence is written in compliance with the guidelines for commas?
a.) Katie’s blanket, which she’s had since she was four, is starting to look scruffy.
b.) Katie’s blanket which she’s had since she was four, is starting to look scruffy.
c.) Katie’s blanket, which she’s had since she was four is starting to look scruffy.
d.) Katie’s blanket which she’s had, since she was four, is starting to look scruffy.