I think the answer is A I'm not 100% though:)
I believe the answer is D because it uses a comma, allowing the word 'screamed' to be lowercased.
Answer:
The weather was a powerful force in the lives of the Norse
Explanation:
'at the mercy of' suggests that they had so control over it, it was something that affected them no matter what they could've done against it. It shows that they had to either stay and let it make they lives a great deal harder or leave and look for a safer area to live out their lives.
Does it sound like me and do I have clear organization.