The correct answer is A) Signal Detection.
Catherine is at a crowded baseball game when she loses track of her son, Nick. Despite the loud cheering and noise of the crowd, she can pinpoint his location when he calls for her because she can distinguish the sound of his voice from all the other voices. This illustrates the Signal Detection theory.
This is an example of the Signal Detection theory because Catherine, as the mother she is, can clearly detect the voice of her son, differentiating it from the voices from the crowd. This theory is also used by psychologists that try to understand the way people make decisions under difficult conditions.