Answer
The correct answer is "Plate A is negatively charged and plate B is positively charged"
Explanation:
In an electric field, the direction depends on the charge of the plate.
For a positively charged plate, the electric field is always directed away from it.
For the negatively charged plate, the electric field will be directed towards it.
Looking ate plate A, the electric field in directing toward it. Therefore, it's a negative charge.
For plate B, the electric field is moving away from it, making it a positively charged plate.