**Core Concept**
Trisomy 13, also known as Patau syndrome, is a rare genetic disorder caused by the presence of an extra copy of chromosome 13. This condition is associated with severe intellectual disability, physical abnormalities, and a high mortality rate.

**Why the Correct Answer is Right**
Trisomy 13 occurs due to the failure of the process of meiosis, resulting in an extra copy of chromosome 13. This extra genetic material disrupts normal development, leading to the characteristic physical and intellectual abnormalities. The presence of an extra chromosome 13 leads to the overexpression of genes on this chromosome, which are involved in various developmental processes.

**Why Each Wrong Option is Incorrect**
**Option A:** This option is typically associated with Trisomy 21, also known as Down syndrome, which is a different genetic disorder.
**Option B:** This option is not a known genetic disorder associated with an extra copy of a chromosome.
**Option C:** This option is not a specific genetic disorder, but rather a broader category of genetic conditions.

**Clinical Pearl / High-Yield Fact**
One key feature of Trisomy 13 is the presence of holoprosencephaly, a condition in which the brain does not properly divide during development. This can lead to severe intellectual disability and other physical abnormalities.

**Correct Answer: D. Trisomy 13.**