If a person is pushing a box inside a moving train,the work done in the frame of the earth will be: (where $\vec{s}$ is the displacement of the box in the train and $\vec{s}_0$ is the displacement of the train relative to the ground)

• A
  $\vec{F} \cdot \vec{s}_0$
• B
  $\vec{F} \cdot \vec{s}$
• C
  $\vec{F} \cdot (\vec{s} + \vec{s}_0)$
• D
  zero