**Core Concept**
The question is testing the student's knowledge of the pathophysiological changes associated with a specific neurodegenerative disorder, specifically the presence of neurofibrillary tangles and another characteristic feature. This is related to the field of geriatric psychiatry and neuropathology.

**Why the Correct Answer is Right**
In Alzheimer's disease, the presence of neurofibrillary tangles is a hallmark feature, composed of hyperphosphorylated tau protein. Alongside these tangles, another characteristic feature is the deposition of beta-amyloid plaques in the brain. These plaques are composed of beta-amyloid peptides that accumulate in the extracellular space, leading to neuronal damage and death. The combination of neurofibrillary tangles and beta-amyloid plaques is a diagnostic hallmark of Alzheimer's disease.

**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because it does not specify the characteristic feature associated with Alzheimer's disease alongside neurofibrillary tangles. While neurofibrillary tangles are indeed a feature of Alzheimer's, the question asks for another characteristic feature.
**Option B:** This option is incorrect because it is unrelated to the pathophysiology of Alzheimer's disease. Lewy bodies are characteristic of Parkinson's disease and dementia with Lewy bodies, not Alzheimer's disease.
**Option C:** This option is incorrect because it refers to a feature of frontotemporal dementia, not Alzheimer's disease. Pick bodies are characteristic of frontotemporal dementia with Pick's disease.
**Option D:** This option is incorrect because it refers to a feature of Huntington's disease, not Alzheimer's disease. Huntington's disease is characterized by the presence of huntingtin protein inclusions.

**Clinical Pearl / High-Yield Fact**
When encountering a patient with progressive memory loss, difficulty with speech, and irritability, consider the possibility of Alzheimer's disease. The presence of neurofibrillary tangles alongside beta-amyloid plaques is a diagnostic hallmark of this condition.

**Correct Answer:** B. Beta-amyloid plaques