Effector organs are the organs that carry out the response or action in response to a stimulus. Among the given options, the skin is an effector organ as it responds to stimuli such as heat, cold, pressure, and pain, by activating various physiological mechanisms such as sweating, shivering, and blood vessel constriction or dilation, to maintain the body's internal balance or homeostasis. The tongue, nose bridge, and ear glands are not considered effector organs as they do not have a direct role in carrying out a physiological response to a stimulus.