Which of the following statements are correct?

A. The relative motion between a magnet and a coil is responsible for induction of electric current in the coil.

B. Magnetic flux is a vector quantity.

C. In a closed coil, the magnitude of emf induced is equal to the time rate of change of magnetic flux.

D. Eddy currents oppose the magnetic braking effect in trains.

E. Lenz's law gives the polarity of the induced emf clearly.

Choose the correct answer from the options given below: