**Core Concept**
Multiple sclerosis (MS) is a chronic autoimmune disease characterized by demyelination of the central nervous system (CNS), leading to various neurological symptoms. The disease involves the immune system attacking the myelin sheath, which is the fatty, insulating layer surrounding nerve fibers, compromising nerve signal transmission.

**Why the Correct Answer is Right**
The correct answer states that multiple sclerosis is an autoimmune disease mainly targeting myelin basic protein (MBP). **Myelin basic protein** is a key component of the myelin sheath, and the immune system's attack on MBP is a crucial aspect of the disease's pathogenesis. The immune system mistakenly identifies MBP as a foreign antigen, triggering an immune response that damages the myelin sheath and disrupts nerve function.

**Why Each Wrong Option is Incorrect**
**Option A:** Multiple sclerosis primarily involves the central nervous system (CNS), which includes the brain and spinal cord, rather than the peripheral nervous system (PNS), which consists of nerves outside the CNS.

**Option B:** Multiple sclerosis is not a malignant condition, and it is not resolved spontaneously. In fact, the disease is characterized by relapses and remissions, with periods of worsening symptoms (relapses) followed by periods of partial or complete recovery (remissions).

**Option C:** Multiple sclerosis is more common in females than in males, with a female-to-male ratio of approximately 3:1. This gender disparity is not fully understood, but hormonal and genetic factors are thought to contribute to the increased risk in females.

**Clinical Pearl / High-Yield Fact**
It's essential to remember that multiple sclerosis is a complex disease with a multifactorial etiology, involving both genetic and environmental factors. The disease can present with a wide range of symptoms, including visual disturbances, weakness, numbness, and cognitive impairment.

**Correct Answer:**
✓ Correct Answer: D. Autoimmune disease mainly targetting MBP.