Which quadrilateral will always have 4-fold reflectional symmetry?

trapezoid
rhombus
square
rectangle

When a geometric figure is folded about a line of symmetry, the two halves match up so if you have copies of the quadrilaterals (you can test lines of symmetry by folding). 

Since a square has four equal sides and angles, it will have reflectional symmetries across four axes. Square can be folded in half over either diagonal, the horizontal segment which cuts the square in half, or the vertical segment which cuts the square in half. So the square has four lines of symmetry. 

The rectangle has only two, as it can be folded in half horizontally or vertically (the rectangle's axes go through the midpoints of the opposite sides).
 
The rhombus has only two, as it can be folded in half horizontally or vertically ( the rhombus' axes go through the opposite vertices).

 The isosceles trapezoid has one set of non-congruent, parallel sides, and one set of congruent sides that are not parallel to each other. This figure will only have one reflectional line of symmetry across the axis, which runs through the midpoints of the parallel sides, and is perpendicular to them.

The correct answer from the choices given is the third option.Square is the quadrilateral that will always have 4-fold reflectional symmetry. You can draw four lines symmetry for this shape. Two lines divide the shape into two rectangles and two lines are the diagonals of the shape.