**Core Concept**
Autosomal dominant diseases are characterized by the presence of a single copy of a dominant allele, leading to the expression of the disease. This type of inheritance pattern is due to the dominant allele's ability to mask the effect of the normal allele, resulting in the manifestation of the disease. Autosomal dominant diseases often have a high penetrance and express themselves in every generation.

**Why the Correct Answer is Right**
The correct answer is likely a disease caused by a mutation in a single gene, which leads to the expression of the disease even if the individual has only one copy of the mutated gene. For example, Huntington's disease is an autosomal dominant neurodegenerative disorder caused by an expansion of a CAG repeat in the Huntingtin gene. This mutation leads to the production of a toxic protein that causes neuronal damage and degeneration.

**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because it may be an autosomal recessive disease, requiring two copies of the mutated gene to express the disease.
**Option B:** This option is incorrect because it may be a sex-linked disease, where the disease expression is linked to the sex chromosome.
**Option C:** This option is incorrect because it may be a multifactorial disease, resulting from the interaction of multiple genetic and environmental factors.

**Clinical Pearl / High-Yield Fact**
A key feature of autosomal dominant diseases is their high penetrance, meaning that if an individual inherits the mutated gene, they are highly likely to express the disease. This is in contrast to autosomal recessive diseases, where the individual must inherit two copies of the mutated gene to express the disease.

**Correct Answer:** C.