The correct answer is C) To release the raft automatically as the ship sinks. The purpose of the hydrostatic release unit on a liferaft is to automatically release the raft from its stowage position as the ship sinks and the unit is submerged under water. This ensures the raft will float to the surface and inflate, rather than remaining attached to the sinking vessel. This automatic release mechanism is required by Coast Guard regulations to improve the chances of survival in an emergency abandon ship situation. The other answer choices are incorrect - option A is not the purpose of the hydrostatic release, option B refers to the inflation mechanism rather than the release, and option D is not correct since C is the right answer.