A. True, a rhombus is a parallelogram with equal sides. A rhombus has four congruent sides.
B. True, but there are two other ways to find the area of a rhombus: there is the "diagonals" method and the "trigonometry" method.
C. False, the area of a rhombus is not less than the area of a parallelogram because it will depend on the diagonals.
D. False, a parallelogram is not always a rhombus because the dimensions and other attributes of a parallelogram may vary while the rhombus will remain equal for all aspects.
E. True, if you use the base times height formula but if you used any of the other formulas this would be false.