I believe a brainstorming hope it helps
Answer:
b. them
Explanation:
their is used to show ownership
Ex: those are THEIR glasses
They is used to refer to a group of people or someones unknown gender
Ex: There THEY are
It is used to refer to objects
Ex: IT is a ball
there is more to it but this is a simple explanation
Either sentence A or B is correct, but I'm leaning towards B more than A. Hope this helps!
It seems like it would be childish
It is allowed to set more