Answer:
Preston sought to take a neutral stance towards both Jane and Kathy, who were arguing about things pertaining not to him.
Yes it is, it has a period therefore a complete sentence.
I would go with C because the possessive pronoun is before it
Answer:
C. Marco is wearing shorts and a T-shirt though it is a chilly morning.
Explanation:
I did that also XD, 12th grade is extremely exhausting