Which of the following diseases is commonly caused by a prion?

Creutzfeldt-Jakob disease is well-established as a prion disease, which distinguishes it from the other options listed. Prions are misfolded proteins that can induce other normal proteins in the brain to also misfold, leading to neurodegenerative disorders. These diseases are characterized by long incubation periods and the accumulation of abnormal prion proteins in neural tissues.

Creutzfeldt-Jakob disease specifically results from the transmission of infectious prions, which can occur through genetic predisposition or exposure to contaminated tissues. The pathological hallmark of this disease is spongiform degeneration in the brain, which is a direct consequence of prion activity.

In contrast, Alzheimer's disease and Parkinson's disease are commonly associated with different types of protein aggregations, namely amyloid-beta and tau proteins in Alzheimer's, and alpha-synuclein in Parkinson's. Multiple sclerosis, on the other hand, is an autoimmune disorder rather than a protein misfolding condition, where the immune system attacks the protective covering of nerves. This differentiation highlights why Creutzfeldt-Jakob disease is correctly identified as the disease associated with prions.