Assertion (A): Replacing water by ethane-1,2-diamine turns the green $[\mathrm{Ni}(\mathrm{H}{}_2\mathrm{O}){}_6]{}^{2+}$ into violet $[\mathrm{Ni}(\mathrm{en}){}_3]{}^{2+}$, and both complexes have two unpaired electrons. Reason (R): en is a stronger-field ligand than water, which increases the splitting ${\Delta }_o$ and shifts absorption to a shorter wavelength, but a $d^8$ ion in an octahedral field always has two unpaired electrons.

1. ABoth A and R are true and R is the correct explanation of A
2. BBoth A and R are true but R is not the correct explanation of A
3. CA is true but R is false
4. DA is false but R is true