A particle of mass 1 mg has the same wavelength as an electron moving with a velocity of $3\times {10}^6 m{s}^{-1}$. The velocity of the particle is 

(a) 2.7$\times {10}^{-18} m{s}^{-1}$

(b) $9\times {10}^{-2} m{s}^{-1}$

(c) $3\times {10}^{-31 }m{s}^{-1}$

(d) $2.7\times {10}^{-21} m{s}^{-1}$

(mass of electrons =$9.1\times {10}^{-31}kg$)