'In particular' is a transitional phrase that we use to elaborate on an idea by introducing examples.
In the example sentence you show says:
I really think that some of my parents' rules are not fair: This is the idea that needs elaboration.
in particular, the one that says I can not talk to my friends on the phone after eight o'clock: This is the example used to support the idea stated previously.
The answer would be "in particular", you labeled it "b" but you might've meant "c"...? Anyway it's "in particular" because that's where the sentence shifts from the main focus to an example that supports it.
