Which of the following complexes are low spin and diamagnetic?

(P) ${\mathrm{K}}_4\left[{\mathrm{O}}_8(\mathrm{CN}{)}_6\right]$     (Q) $\left[\mathrm{Mo}(\mathrm{CO}{)}_6\right]$

(R) ${\left[\mathrm{Mn}(\mathrm{CN}{)}_6\right]}^{4-}$

Select the correct answer using the codes given below:

Since ${\mathrm{K}}_4\left[{\mathrm{O}}_8(\mathrm{CN}{)}_6\right],\left[\mathrm{Mo}(\mathrm{CO}{)}_6\right]$ has no unpaired electrons they are diamagnetic and low spin while  ${\left[\mathrm{Mn}(\mathrm{CN}{)}_6\right]}^{4-}$ has one unpaired electron they are paramagnetic in nature and have high spin. 

The option B is correct.