**Core Concept**
Polymerase chain reaction (PCR) is a laboratory technique used to amplify specific DNA sequences. It relies on the use of heat-stable DNA polymerase enzymes, primers, and nucleotides to create multiple copies of a target DNA sequence.

**Why the Correct Answer is Right**
The correct answer is related to the mechanism of PCR. The process involves denaturation of the template DNA, followed by the annealing of primers to the target sequence, and finally the extension of the primers by DNA polymerase. This cycle is repeated multiple times, resulting in exponential amplification of the target DNA sequence. The high specificity of PCR is due to the use of primers that are complementary to the target sequence.

**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect as it does not describe a key feature of PCR. While PCR does involve the use of nucleotides, this is not the most distinctive aspect of the technique.

**Option B:** This option is incorrect as it describes a different laboratory technique altogether. The process of gel electrophoresis is used to separate and analyze DNA fragments based on size, but it is not related to PCR.

**Option C:** This option is incorrect as it describes a different type of DNA amplification technique. The technique of rolling circle amplification is used to amplify circular DNA molecules, but it is not the same as PCR.

**Clinical Pearl / High-Yield Fact**
A key point to remember about PCR is that it is highly sensitive and specific, allowing for the detection and amplification of very small amounts of target DNA. This makes it a powerful tool in molecular diagnostics.

**Correct Answer: D. Amplification of the target DNA sequence occurs exponentially with each cycle.**