**Core Concept**
Intracranial aneurysms are abnormal dilations of blood vessels within the brain, which can be life-threatening if they rupture. A definitive test for evaluating intracranial aneurysms is crucial for diagnosis and management.

**Why the Correct Answer is Right**
Digital Subtraction Angiography (DSA) is considered the gold standard for evaluating intracranial aneurysms. This imaging technique involves injecting a contrast agent into the blood vessels and then subtracting the background structures from the image, allowing for detailed visualization of the vascular anatomy. DSA can accurately diagnose the presence, location, size, and shape of intracranial aneurysms, as well as assess their potential for rupture. The high spatial resolution and three-dimensional imaging capabilities of DSA make it an essential tool for neurosurgeons and interventional neuroradiologists.

**Why Each Wrong Option is Incorrect**
**Option A:** Computed Tomography (CT) Angiography is a non-invasive imaging technique that can provide information on the size and location of intracranial aneurysms. However, it may not provide the same level of detail as DSA, and its accuracy can be influenced by factors such as beam hardening and artifacts.
**Option B:** Magnetic Resonance Angiography (MRA) is a non-invasive imaging technique that can provide detailed images of the blood vessels. However, it may not be as sensitive as DSA for detecting small aneurysms or those with complex morphology.
**Option C:** Transcranial Doppler Ultrasound is a non-invasive imaging technique that can provide information on blood flow and vessel diameter. However, it is not suitable for evaluating the morphology of intracranial aneurysms.

**Clinical Pearl / High-Yield Fact**
DSA is a critical tool for neurosurgeons and interventional neuroradiologists, and its accuracy is essential for making informed decisions about treatment options for intracranial aneurysms.

**Correct Answer:** C. Digital Subtraction Angiography (DSA)