**Core Concept**
Migraine is a complex neurological disorder characterized by recurrent episodes of headache, often accompanied by sensory sensitivities, nausea, and vomiting. Assessing disability in migraine is crucial for evaluating the impact of the condition on a patient's quality of life.

**Why the Correct Answer is Right**
The Migraine Disability Assessment (MIDAS) is a widely used questionnaire to evaluate the level of disability caused by migraine. It assesses the frequency and severity of migraine attacks, as well as their impact on daily activities, work, and social life. The MIDAS score is calculated by summing the total number of days missed from work or school, and the number of days with reduced productivity due to migraine. This score helps clinicians to determine the severity of migraine-related disability and monitor treatment effectiveness.

**Why Each Wrong Option is Incorrect**
**Option A:** The Headache Impact Test (HIT) is a self-administered questionnaire that assesses the impact of headache on daily life, but it is not specifically designed to evaluate disability in migraine.
**Option B:** The Visual Analog Scale (VAS) is a tool used to measure pain intensity, but it does not assess disability or functional impairment.
**Option C:** The International Classification of Headache Disorders (ICHD) is a diagnostic criteria for headache disorders, including migraine, but it does not evaluate disability.

**Clinical Pearl / High-Yield Fact**
The MIDAS score can be used to monitor changes in migraine-related disability over time and to evaluate the effectiveness of treatment interventions.

**Correct Answer: C. Migraine Disability Assessment (MIDAS)**