The complex ion [Fe (CN)₆]^4- contains :

EAN=Z−X+Y
Z=Atomic number of the metal
X=Number of electrons lost during the formation of the metal ion from its atom
Y=Number of electrons donated by the ligands
For [Fe(CN)_6​]⁴⁻
EAN=Z−X+Y=26−2+12=36.
Thus total of 36 electrons are present on Fe²⁺ cation.
Thus option 1 is correct.
The complex [Fe(CN)₆​]⁴⁻ involves d²​sp³​ hybridization and has octahedral geometry.
Thus option 2 is incorrect.
Total number of electrons in [Fe(CN)₆​]⁴⁻ is 36+6(12)=108. Thus, option 3 is incorrect.
The complex contains 12 sigma bonds. Six are between Fe and C and six are present in six CN ligands. Thus, option 4 is incorrect.