The correct option is
A Square
- All sides are of equal length.
- All angles are right angles.
- Opposite sides are parallel.
- Diagonals are of equal length.
Square satisfies all the above characteristics.
A square would look like:
⇒AB=BC=CD=DA⇒AC=BD⇒m∠A=m∠B=m∠C=m∠C=90∘