**Core Concept**
The concept being tested here is the inheritance pattern of genes, specifically when a baby inherits a functional gene from only one parent. This is related to the field of genetics and the study of Mendelian inheritance patterns.

**Why the Correct Answer is Right**
When a baby inherits a functional gene from only one parent, it means that the gene is present on only one allele of the gene pair. This is known as an autosomal dominant pattern of inheritance. In this case, the gene is dominant over the other allele, which is usually a recessive allele. The presence of one copy of the dominant allele is enough to express the trait. This is in contrast to autosomal recessive inheritance, where a baby needs to inherit two copies of the recessive allele (one from each parent) to express the trait.

**Why Each Wrong Option is Incorrect**
* **Option A:** This option is not provided, so we cannot discuss it.
* **Option B:** This option is also not provided, so we cannot discuss it.
* **Option C:** This option is not provided, so we cannot discuss it.
* **Option D:** This option is also not provided, so we cannot discuss it.

**Clinical Pearl / High-Yield Fact**
It's essential to remember that autosomal dominant inheritance patterns are characterized by the presence of one copy of the dominant allele being enough to express the trait. This is in contrast to autosomal recessive inheritance, where two copies of the recessive allele are needed.

**Correct Answer:** C. Uniparental disomy