Question

parallelogram rhombus square rectangle a is always a rhombus, but a rhombus is not always a

Explanation:

Step1: Analyze the properties of each shape

A parallelogram is a quadrilateral with opposite sides parallel. A rhombus is a parallelogram with all sides equal. A square is a special case of a rhombus (and a rectangle) with all sides equal and all angles \(90^{\circ}\). A rectangle is a parallelogram with all angles \(90^{\circ}\).

Step2: Check the relationship

A rhombus has all sides equal. A rectangle has opposite sides equal (and all angles \(90^{\circ}\)). A rectangle is not always a rhombus (unless it's a square). A square is a rhombus. A parallelogram may not have all sides equal (so not a rhombus in general).

Answer:

rectangle