$\therefore \lambda = \frac{6.626 \times 10^{-34} \,\, Js}{1.67 \times 10^{-27} \times 10^{3} \, kg \cdot\, m\, s^{-1}}$
$= \frac{3.97 \times 10^{-10} \,kg \cdot \,m^2 \cdot s^{-2} \cdot s}{kg \cdot \,m \cdot \,s^{-1}}$
$=3.97 \times 10^{-10} \,m = 0.397 \times 10^{-9} \,m = 0.397\, nm$
$ \simeq 0.40 \, nm$
$(A)$ $n=3,1=0, m=0$
$(B)$ $n=4,1=0, m=0$
$(C)$ $n =3,1=1, m =0$
$(D)$ $n=3,1=2, m=1$