**Core Concept**
The question describes a clinical presentation of a patient with progressive dementia and intermittent irregular jerky movements, accompanied by characteristic EEG findings. This scenario is suggestive of a specific neurodegenerative disorder characterized by the presence of periodic sharp biphasic waves on EEG.

**Why the Correct Answer is Right**
The clinical presentation and EEG findings are consistent with a diagnosis of **Progressive Supranuclear Palsy (PSP)**, a neurodegenerative disorder that presents with progressive dementia, parkinsonism, and supranuclear vertical gaze palsy. The presence of periodic sharp biphasic waves on EEG is a characteristic feature of PSP. These waves are thought to be related to the abnormal activity of the thalamocortical circuits in PSP.

**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because it does not match the clinical presentation and EEG findings described in the question. Although **Creutzfeldt-Jakob Disease (CJD)** can present with dementia and myoclonus, the EEG findings in CJD are typically characterized by periodic sharp wave complexes, not biphasic waves.
**Option B:** This option is incorrect because **Alzheimer's Disease (AD)** does not typically present with myoclonus or characteristic EEG findings like periodic sharp biphasic waves.
**Option C:** This option is incorrect because **Huntington's Disease (HD)** does not typically present with dementia and myoclonus in the same way as PSP.

**Clinical Pearl / High-Yield Fact**
It's essential to remember that the presence of periodic sharp biphasic waves on EEG is highly suggestive of Progressive Supranuclear Palsy (PSP). This finding can help differentiate PSP from other neurodegenerative disorders that present with dementia and myoclonus.

**Correct Answer: B.**