Question

Which sentence uses a verb that agrees with its subject?

Answer 1

The sentence uses a verb that agrees with its subject would be sentence D. 
Pictures of my great-grandfather hang on the wall above the fireplace. 

- In sentence A, the word "are" should have been used instead of the word "is"
- In sentence B, the word "have" should have been used instead of the word "has"
- In sentence C, the word "doesn't" should have been used instead of the word "don't"

Answer 2

B. 
The articles in that magazine usually has helpful information.
Is it right?