Geometry

Question Analysis
This question tests the ability to derive the contrapositive of a statement about rhombuses and their diagonals.

Key Concept Explanation:
The contrapositive of "If P, then Q" is "If not Q, then not P."

Step-by-Step Solution:
Original statement: "If a shape is a rhombus (P), then its diagonals are perpendicular (Q)."
Contrapositive: "If a shape's diagonals are not perpendicular (not Q), then it is not a rhombus (not P)."
The correct answer is B.

Option Analysis:
A: This is the converse, not the contrapositive.
B: Correct contrapositive.
C: This is the inverse, not the contrapositive.