A rhombus is a type of rhomboid that has:

A rhombus is defined as a quadrilateral with all four sides of equal length. This characteristic is what distinguishes it from other types of quadrilaterals and makes it a specific case of a parallelogram. In a rhombus, opposite angles are equal, and adjacent angles are supplementary, but the key feature is that all sides are equal. This uniformity in side lengths ensures that a rhombus retains its geometric properties, such as maintaining the same distance between opposite sides, which is not true for other shapes like rectangles or general parallelograms where the sides can be of different lengths.

The other options do not accurately describe a rhombus. A rhombus does not have all angles equal; that characteristic belongs to a square. The suggestion of only having two sides is incorrect because a rhombus, like all quadrilaterals, has four sides. Lastly, a rhombus certainly does not have all sides of different lengths, as this would exclude it from being classified as a rhombus. Therefore, the defining trait of having all sides of equal length confirms the answer as correct.