Read the passage carefully and answer.

The crystal field theory (CFT) is an electrostatic model which considers the metal-ligand bond to be ionic arising purely from electrostatic interactions between the metal ion and the ligand. Ligands are treated as point charges in case of anions or dipoles in case of neutral molecules. The five d orbitals in an isolated gaseous metal atom/ion have same energy, i.e., they are degenerate. This degeneracy is maintained if a spherically symmetrical field of negative charges surrounds the metal atom/ion. However, when this negative field is due to ligands (either anions or the negative ends of dipolar molecules like $NH_3$ and $H_2O$) in a complex, it becomes asymmetrical and the degeneracy of the d orbitals is lifted. It results in splitting of the d orbitals. The pattern of splitting depends upon the nature of the crystal field.

The colour of coordination compounds is attributed to

d-d transition

The correct answer is Option (2) → d-d transition

The color of coordination compounds arises due to electronic transitions between d-orbitals split by the crystal field.

• This is called a d–d transition, where an electron jumps from a lower-energy d orbital (tâ‚‚g) to a higher-energy d orbital ($e_g$) in an octahedral or tetrahedral field.
• Other transitions like s–p, d–f, or p–p* are not responsible for the typical colors of transition metal complexes.