Chemistry · Structure of atom

Given below are two statements: one is labelled as Assertion (A) and the other is labelled as Reason (R).\n Assertion (A): Copper has the outer electronic configuration of \( 3d^{10} 4s^1 \) instead of \( 3d^9 4s^2 \).\n Reason (R): Fully filled and half-filled subshells have extra stability due to high exchange energy and symmetrical distribution. \nIn the light of the above statements, choose the correct answer from the options given below:

1. Both (A) and (R) are true and (R) is the correct explanation of (A).
2. Both (A) and (R) are true but (R) is NOT the correct explanation of (A).
3. (A) is true but (R) is false.
4. (A) is false but (R) is true.