**Core Concept**
Brodman's areas are cytoarchitectonic maps of the cerebral cortex, specifically the frontal, parietal, temporal, and occipital lobes. These areas are named after Korbinian Brodmann, a neurologist who first described them in 1909. Each area is characterized by a distinct layering pattern of neurons and is associated with specific functions, including motor control.

**Why the Correct Answer is Right**
The motor area, also known as the primary motor cortex, is responsible for controlling voluntary movements of the body. It is located in the precentral gyrus of the frontal lobe and is organized in a somatotopic manner, meaning that different parts of the body are represented in specific areas of the cortex. The motor area sends signals to the spinal cord and brainstem to initiate and control movements. The correct Brodman's area number for the motor area is 4.

**Why Each Wrong Option is Incorrect**
**Option A:** This is incorrect because area 4 is the primary motor cortex, while area 6 is the premotor cortex, which is involved in planning and coordinating movements.
**Option B:** This is incorrect because area 1, 2, and 3 are involved in sensory processing, including touch and proprioception.
**Option C:** This is incorrect because area 8 is involved in eye movements and other functions, but not motor control.

**Clinical Pearl / High-Yield Fact**
Remember that Brodman's areas are not directly related to clinical syndromes, but understanding their functions can help you interpret neurological examination findings and imaging studies.

**Correct Answer: D. 4. Primary motor cortex**