Is this a multiple choice question? If not, than here is my answer: African Americans was a cause of the Great Migration. Hope I helped.
Answer:
"I'm going to see The Great Gatsby at the cinema", said Dave.
"Have you read the book?", asked Julia.
"I haven't", said Dave.
"It's really good, i can lend it to you", said julia.
"That's very kind of you Julia", said Dave
Explanation:
B. It's hot outside.
Here, the word it's stands for - it is.
Its is used as a possessive - The dog wagged its tail.