The correct answer is C) limit the spread of the fire and control the amount of heat produced. The primary function of an automatic sprinkler system is to detect the presence of a fire, activate, and release water to control and limit the spread of the fire. Sprinklers are designed to contain the fire, prevent it from growing larger, and reduce the heat output, rather than to instantly extinguish the fire or alert the crew. While sprinklers can help protect people in the affected areas, this is a secondary function. Option A is incorrect as sprinklers are not intended to extinguish the fire immediately. Option B is incorrect as protecting people is not the primary purpose. Option D is incorrect as sprinklers do not primarily alert the crew, though they may do so as a secondary function.