Suppose all the people in the world line up at the equator and all start running at speed $v_{rel}$ relative to the surface of the Earth along the equatorial circle. The initial angular velocity of the Earth is $\omega_0$. Let the moment of inertia of the Earth be $I_E$,the moment of inertia of all people be $I_P$,and the radius of the Earth be $R$. Which of the following statements is correct?

• A
  There will be no change in the angular velocity of rotation of the Earth.
• B
  If people run due east,the change in angular velocity of the Earth will be $\omega_0 - \frac{I_P v_{rel}}{(I_P + I_E)R}$.
• C
  If people run due west,the change in angular velocity of the Earth will be $\omega_0 + \frac{I_P v_{rel}}{(I_E)R}$.
• D
  If people run due west,the angular velocity of the Earth will increase.