In the electronic spectrum of [IrBr₆]²⁻, the number of charge transfer band(s) and their origin are, respectively

Charge Transfer complex:

• A charge transfer complex or an electron donor-acceptor complex describes a type of assembly of two or more molecules or ions.
• Charge transfer complex is of 4 types, these are 
  • Ligand to metal charge transfer (LMCT),
  • Metal to ligand charge transfer (MLCT),
  • Ligand-to-ligand charge transfer (LLCT), and
  • Metal-to-metal charge transfer (MMCT).​
• It is a correlation between the energies of charge transfer absorptions and the electrochemical properties of metals and ligands.
• Charge transfer transitions are not restricted by the selection rules that involve ‘d–d ’ transitions, The probability of these electronic transitions is very high, and the absorption bands are therefore intense.

​LMCT:

• The transfer of an electron from an orbital primarily ligand character to one with primarily metal character is known as ligand-to-metal charge transfer or LMCT.
• LMCT occurs if a ligand that can be easily oxidized is bound to a metal center in a high oxidation state, which is readily reduced.

Explanation:-

• In [IrBr6]2−, the oxidation state of Ir is +4 and Ir⁴⁺ is in low spin state.
• [IrBr6]2− is an octahedral complex and the electronic configuration, of Ir4+(d5) is t_2g⁵e_g⁰.
• Given below is a MO diagram for ML₆ octahedral complex

• The 5 t2g electrons of Ir4+(d5 or  t2g5eg0) will occupy the t_2g non-bonding orbitals (HOMO).
• This will result in two LMCT transitions from 

σ → t2g and σ → eg.

Conclusion:-

• Hence, Two, ligand → metal (σ → t2g and σ → eg)  is the correct answer.