Final answer:
The limbic system is the perceptual system that helps shield individuals from unpleasant emotions by regulating emotional responses, particularly those related to fear.
Step-by-step explanation:
The perceptual system that shields individuals from unpleasant emotions is the b) Limbic system. This system includes several brain structures, such as the amygdala, hippocampus, thalamus, and hypothalamus, which play key roles in regulating emotions. The limbic system is critically involved in processing emotional responses and in the modulation of fear. The amygdala, in particular, is significant for the sensation of fear and for recognizing fearful faces. Additionally, the limbic system is involved in memory formation, which can also affect emotional experiences.