Let's go through the answer choices to see which are true statements, and which are false.
A) This is false because consecutive sides must meet up at a vertex point, or else they won't be next to each other. Consecutive sides can never be parallel (regardless what type of quadrilateral we're dealing with, or any polygon for that matter). In other words, consecutive sides share a common point on both segments, which is why they're not parallel. Instead, it should be phrased as "opposite sides of a rhombus are parallel" which is a true statement.
B) This is true. If the diagonals are perpendicular, then we could have either a kite or a rhombus.
C) This is false. If the diagonals are congruent, then we have a rectangle. We could have a square (which is both a rhombus and a rectangle at the same time), but that's only for specific cases. In a more general sense, we could have a non-square rectangle that isn't a rhombus.
D) This is false. A rhombus is a type of parallelogram. For any parallelogram, the opposite angles are always the same measure. The only time the angles are supplementary is when we have a rectangle; otherwise, the angles won't add to 180.
