**Core Concept**
Delusions are fixed, false beliefs that are not amenable to change in light of conflicting evidence. This condition is often associated with a disorder of the brain's neural circuitry, particularly involving the prefrontal cortex and other areas responsible for executive function, decision-making, and reality testing.

**Why the Correct Answer is Right**
Delusions are typically seen in psychotic disorders such as schizophrenia, where the prefrontal cortex's ability to filter and process sensory information is impaired. This impairment allows abnormal, delusional thoughts to dominate the individual's perception of reality. The prefrontal cortex is also responsible for executive function, including the ability to inhibit impulsive thoughts and behaviors.

**Why Each Wrong Option is Incorrect**
**Option A:** Incorrect because delusions can also occur in mood disorders, such as bipolar disorder, but the underlying pathophysiology is more closely related to abnormalities in the prefrontal cortex.

**Option B:** Incorrect because, although disorders of the parietal cortex can lead to spatial disorientation and other cognitive impairments, they are not typically associated with the development of delusions.

**Option C:** Incorrect because, while disorders of the limbic system can influence mood and emotional regulation, they are not directly linked to the development of delusions.

**Clinical Pearl / High-Yield Fact**
Delusions are a key feature of psychotic disorders, and their presence can be a critical determinant in the diagnosis and treatment of these conditions. Clinicians should always consider the possibility of a psychotic disorder in patients presenting with delusions.

**Correct Answer: C. Limbic System**