Assertion (A): The first ionization enthalpy of aluminum is lower than that of magnesium.
Reason (R): Ionic radius of Al³⁺ is smaller than that of Mg²⁺.
A. Both (A) and (R) are true, and (R) is the correct explanation of (A).
B. Both (A) and (R) are true, but (R) is not the correct explanation of (A).
C. (A) is true, but (R) is false.
D. (A) is false, but (R) is true