Which of the following statements is always true? (the first I put B, but I was not sure if I was correct) A. A parallelogram is a rectangle. B. A square is a rhombus. C. A rhombus is a square. D. A rectangle is a square.

The definitions of the quadrilaterals:

A parallelogram is a quadrilateral which has two pairs of parallel sides.

A rectangle is a quadrilateral which has two pairs of parallel sides and four right angles.

A rhombus is a quadrilateral which has two pairs of parallel sides and all of sides are equal in length.

A square is a quadrilateral which has two pairs of parallel sides, all of its sides are equal in length and all of its angles are right.

Now look at your options:

A:

A parallelogram is a rectangle only when its angles are right, so it's not always true.

B:

A square always has four sides equal in length, so it's always a rhombus. Always true.

C:

A rhombus is a square only when its angles are right, so it's not always true.

D:

A rectangle is a square only when its sides are equal in length, so it's not always true.

The correct answer is B.