**Core Concept**
Parent-of-origin-specific gene expression is a phenomenon where the same gene exhibits different expression levels or patterns depending on whether it was inherited from the mother or the father. This concept has significant implications in various fields, including genetics, epigenetics, and developmental biology.

**Why the Correct Answer is Right**
The correct answer refers to the phenomenon of gene expression being influenced by the parental origin of the allele. This is often observed in imprinted genes, where the expression of the gene is determined by the parent of origin. For example, the insulin-like growth factor 2 (IGF2) gene is imprinted, meaning that it is expressed only from the paternal allele, while the maternal allele is silenced. This differential expression is mediated by the action of specific enzymes, such as DNA methyltransferases, which modify the DNA methylation status of the gene.

**Why Each Wrong Option is Incorrect**
* **Option A:** This option is incorrect because it does not specifically refer to the phenomenon of gene expression being influenced by the parental origin of the allele.
* **Option B:** This option is incorrect because it refers to a different concept in genetics, where the expression of a gene is influenced by its location on a particular chromosome.
* **Option C:** This option is incorrect because it refers to a specific type of gene expression regulation, but it does not specifically relate to the parental origin of the allele.

**Clinical Pearl / High-Yield Fact**
Imprinted genes are often involved in developmental processes, and their dysregulation can lead to various diseases, including cancer and neurological disorders. For example, the Beckwith-Wiedemann syndrome is a disorder caused by the overexpression of imprinted genes, including IGF2.

**Correct Answer: D. Genomic imprinting**