Answer:
A, D, E
Explanation:
You want to know the properties applicable to a square among those listed.
Quadrilateral
Quadrilaterals can be classified according to the relationships between their sides. These relationships also give rise to relationships between the diagonals.
The diagonals have the same midpoint in a parallelogram.
The diagonals are the same length in a parallelogram that is a rectangle.
Square
A square is a rectangle that has adjacent sides of the same length (A). That means its diagonals have the same midpoint (E), and they are the same length (D).
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Additional comment
When segments have the same slope, they are parallel. Consecutive sides intersect, so cannot have the same slope (E). Likewise, the diagonals intersect, so cannot have the same slope (C).