**Core Concept**
The motor migration complex is a crucial component of the developing brain, responsible for the migration of neurons during embryonic development. This complex plays a vital role in the formation of the cerebral cortex, and any disruptions in this process can lead to various neurological disorders.

**Why the Correct Answer is Right**
The motor migration complex, also known as the radial glial scaffold, facilitates the migration of neurons through the action of various cytoskeletal components. The rate of migration is primarily regulated by the interaction between the neuron's microtubules and the radial glial fibers. This interaction allows the neuron to move along the radial glial fibers, which serve as a guide for the migrating neurons. The rate of migration is influenced by the presence of specific cytoskeletal proteins, such as microtubule-associated proteins (MAPs), which help to regulate the dynamics of microtubule assembly and disassembly.

**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because it does not provide a specific rate of migration, making it a vague and non-specific choice.
**Option B:** This option is incorrect because it suggests a rate of migration that is too rapid, which is not consistent with the slow and gradual process of neuronal migration.
**Option C:** This option is incorrect because it suggests a rate of migration that is too slow, which is not consistent with the observed rates of neuronal migration in vivo.

**Clinical Pearl / High-Yield Fact**
It is essential to note that disruptions in the motor migration complex can lead to various neurological disorders, including lissencephaly and pachygyria. These disorders are characterized by abnormal brain morphology and can result in severe cognitive and motor impairments.

**Correct Answer: D. 5 μm/min**