Why Can Scratching or Chipping the Seed Coat Speed Up

Why can scratching or chipping the seed coat speed up the germination of hard-coated seeds like alfalfa?

A) The mechanical stress activates hydrolytic enzymes.
B) Water and oxygen can enter the seed to reach the embryo more quickly.
C) Carbon dioxide can enter the seed and stimulate photosynthesis.
D) Bacteria or fungi can enter the seed and release growth factors.