Answer:
Its B
Step-by-step explanation:
thats the relative minor of the C major scale wich has no alteration because its the 6th grade of that scale, it is a little bit complicated to explain in text but trust me, its B.
You could say A its also minor but thats melodic minor, wich it is a diferent thing.
Contact me if you need any help with music homework, im kinda advanced in music and i can help you with probably anything you need.
Good luck!