Assertion (a): Cu²⁺ ions are more stable than cu ions in aqueous solutions.
Reason (r): Cu ion has higher hydration enthalpy than Cu²⁺.

A. If both assertion and Reason are true, and reason is the true explanation of the assertion.
B. If both assertion and reason are true, but reason is not the true explanation of the assertion.
C. If assertion is true, but reason is false
D. If both assertion and reason are false