A block of mass \(m\) rests on a rough horizontal surface. A horizontal force \(F\) is applied to the block. The coefficient of static friction is \(\mu_s\) and the coefficient of dynamic friction is \(\mu_d\). Which statement is correct?

• A

  The block starts moving when \(F > \mu_d mg\).

• B

  The frictional force is always equal to \(\mu_d mg\) while the block is moving.

• C

  The frictional force is equal to \(F\) if the block remains stationary.

• D

  The frictional force is always equal to \(\mu_s mg\) before the block starts moving.