The velocity acquired by a body moving with uniform acceleration is 30 ms^-1 in 2 s and 60 ms^-1 in 4 s. The initial velocity is

• A

  zero

• B

  $2{\mathrm{ms}}^{-1}$

• C

  $3{\mathrm{ms}}^{-1}$

• D

  $10{\mathrm{ms}}^{-1}$