**Core Concept**
The globus pallidus and putamen are structures within the basal ganglia, a group of nuclei and tracts in the brain involved in movement control and cognition. These structures are part of the lentiform nucleus, which is a key component of the basal ganglia circuitry.

**Why the Correct Answer is Right**
The globus pallidus and putamen are located in the lentiform nucleus, which is situated in the basal ganglia. The lentiform nucleus is a result of the fusion of the globus pallidus and putamen. The globus pallidus is a structure that plays a crucial role in the regulation of voluntary movement, while the putamen is involved in the processing of sensory information and motor control.

**Why Each Wrong Option is Incorrect**
* **Option A:** This option is incorrect because the globus pallidus and putamen are not located in the thalamus, which is a different structure in the brain.
* **Option B:** This option is incorrect because the hippocampus is a part of the limbic system, not the basal ganglia.
* **Option C:** This option is incorrect because the substantia nigra is another structure within the basal ganglia, but it is not where the globus pallidus and putamen are located.

**Clinical Pearl / High-Yield Fact**
The basal ganglia circuitry is critical for the regulation of movement, and dysfunction in this circuitry can lead to movement disorders such as Parkinson's disease. The lentiform nucleus is a key component of this circuitry, and damage to the globus pallidus or putamen can result in movement abnormalities.

**Correct Answer:** C. The lentiform nucleus.