**Core Concept**
Frameshift mutations are a type of genetic mutation that occurs due to the insertion or deletion of nucleotides in a DNA sequence. This disruption in the normal sequence of nucleotides leads to a shift in the reading frame of the genetic code, resulting in the synthesis of a completely different protein product.

**Why the Correct Answer is Right**
A frameshift mutation occurs when one or more nucleotides are inserted or deleted from a DNA sequence, which changes the reading frame of the genetic code. This can be due to the insertion of a nucleotide into a DNA sequence, which is known as an insertion mutation. The inserted nucleotide disrupts the normal sequence of nucleotides, leading to a shift in the reading frame and resulting in a completely different protein product. This type of mutation is particularly significant in the context of genetic disorders, as it can lead to the synthesis of a non-functional protein or a protein with a completely different function.

**Why Each Wrong Option is Incorrect**
**Option A:** Transition mutations involve the substitution of one purine for another (A for G) or one pyrimidine for another (C for T), but they do not involve the insertion or deletion of nucleotides, which is characteristic of frameshift mutations.

**Option B:** Transversion mutations involve the substitution of a purine for a pyrimidine or vice versa (A for C, G for T, etc.), but they do not involve the insertion or deletion of nucleotides, which is characteristic of frameshift mutations.

**Option D:** Point mutations involve the substitution of a single nucleotide in a DNA sequence, but they do not involve the insertion or deletion of nucleotides, which is characteristic of frameshift mutations.

**Clinical Pearl / High-Yield Fact**
Frameshift mutations are a key cause of genetic disorders such as sickle cell anemia, cystic fibrosis, and Huntington's disease. These mutations can lead to the synthesis of a non-functional protein or a protein with a completely different function, resulting in the development of a genetic disorder.

**✓ Correct Answer: C. Inseion Insertion**