**Core Concept**
Down Syndrome is a genetic disorder caused by an abnormality in the number of chromosomes, specifically an extra copy of chromosome 21. The most common cause is trisomy 21, where there are three copies of chromosome 21 instead of the usual two. Balanced translocations involving chromosome 21 are another cause, where a part of chromosome 21 breaks off and attaches to another chromosome. This can lead to the production of gametes with an extra copy of chromosome 21, resulting in Down Syndrome.

**Why the Correct Answer is Right**
Option C, t(11;14), is a balanced translocation involving chromosomes 11 and 14, but not chromosome 21. This type of translocation is not associated with Down Syndrome, as it does not involve the extra copy of chromosome 21. In contrast, the other options involve chromosome 21 and are associated with Down Syndrome: A (t(14;21)) and D (t(15;21)) are balanced translocations involving chromosome 21, while B (Trisomy 21) is the most common cause of Down Syndrome.

**Why Each Wrong Option is Incorrect**
**Option A:** t(14;21) is a balanced translocation involving chromosome 21, which is associated with Down Syndrome.
**Option B:** Trisomy 21 is the most common cause of Down Syndrome, involving an extra copy of chromosome 21.
**Option D:** t(15;21) is another balanced translocation involving chromosome 21, also associated with Down Syndrome.

**Clinical Pearl / High-Yield Fact**
Down Syndrome can also be caused by mosaicism, where only some cells have an extra copy of chromosome 21, while others have the usual two copies. This can lead to variable symptoms and severity of the condition.

**Correct Answer:**
✓ Correct Answer: C. t(11 : 14)