A rhombus is a parallelogram with four equal sides. In addition to having four equal sides, rhombi also have diagonals that bisect each other. This means that the diagonals intersect each other at a 90-degree angle, and the point of intersection is the midpoint of both diagonals.
Option A is, therefore, the correct answer: "Diagonals bisect each other" is the property that makes rhombi different from other parallelograms. Option B is true for all parallelograms. Option C is true for squares, which are a type of rhombus with right angles, but not for all rhombi. Option D is true for some special types of parallelograms, such as rectangles, but not for all rhombi