Which of the following d-electron distribution of the diamagnetic complex `[Ni(CN)]^(2-)` is possible according to the crystal field theory ?

According to crystal field theory (CFT) :

Which of the following paramagnetic complex with two unpaired electrons in t_(2g) orbital according to crystal field theory

Which of the following energy diagrams shows the electron distribution according to the crystal field model of the 3d-electrons in [CoCl_(4)]^(2-) ?

Which of the following energy diagrams shows the electron distribution according to the crystal field model of the 3d-electrons in [CoCl_(4)]^(2-) ?

[Ni(CN)_4 ]^(2-) is diamagnetic ,while [NiCl_4]^(2) - is paramagnetic ,explain using crystal field theory.