Geometry

Question Analysis
This question involves identifying the contrapositive of a statement about rhombuses and their diagonals, requiring knowledge of quadrilateral properties.

Key Concept Explanation:
The contrapositive of "If P, then Q" is "If not Q, then not P."
It is logically equivalent to the original statement.

Step-by-Step Solution:
Original statement: "If a quadrilateral is a rhombus (P), then its diagonals bisect each other at right angles (Q)."
Contrapositive: "If a quadrilateral's diagonals do not bisect each other at right angles (not Q), then it is not a rhombus (not P)."
The contrapositive is true because it is logically equivalent to the original statement.

Option Analysis:
A: Correct contrapositive and true.
B: This is the converse, which is false (e.g., a kite has diagonals ...