**Core Concept**
DNA (Deoxyribonucleic acid) is a self-replicating molecule essential for the transmission of genetic information from one generation to the next. It is composed of nucleotides, each containing a sugar molecule called deoxyribose, a phosphate group, and one of four nitrogenous bases: adenine (A), guanine (G), cytosine (C), and thymine (T).

**Why the Correct Answer is Right**
DNA is synthesized from nucleotides, which are the building blocks of DNA. The process of DNA synthesis involves the pairing of nucleotides according to base pairing rules, where adenine pairs with thymine and guanine pairs with cytosine. This base pairing is crucial for the stability and replication of DNA. The enzyme DNA polymerase catalyzes the formation of phosphodiester bonds between the sugar molecules of adjacent nucleotides, resulting in the formation of a new DNA strand.

**Why Each Wrong Option is Incorrect**
**Option A:** This option is not applicable as it does not describe a valid process for DNA formation.
**Option B:** While RNA (ribonucleic acid) is formed from nucleotides, it is not the direct precursor to DNA formation.
**Option C:** This option is incorrect as it does not describe the specific process of DNA synthesis from nucleotides.

**Clinical Pearl / High-Yield Fact**
The base pairing rules in DNA synthesis are crucial for maintaining genetic integrity and preventing mutations. A classic example of the importance of these rules is the genetic disorder sickle cell anemia, which results from a point mutation in the HBB gene where adenine pairs with uracil instead of thymine.

**Correct Answer: B. RNA (ribonucleic acid) is synthesized from nucleotides and serves as a template for DNA synthesis through a process known as transcription.