**Core Concept**
Microarray is a laboratory technique used for high-throughput analysis of gene expression, where thousands of genes are analyzed simultaneously to understand their expression levels in various conditions. This technique relies on the hybridization of labeled nucleic acid probes to complementary DNA or RNA sequences immobilized on a solid surface. By analyzing the intensity of the hybridization signal, researchers can determine the relative abundance of specific messenger RNA (mRNA) molecules in a given sample.

**Why the Correct Answer is Right**
Microarray is primarily used to study gene expression, which is the process by which the information encoded in a gene's DNA is converted into a functional product, such as a protein. Gene expression is regulated by various factors, including transcription factors, epigenetic modifications, and environmental stimuli. By comparing the gene expression profiles of different cell types, tissues, or disease states, researchers can identify genes that are differentially expressed, which can provide insights into the underlying biological mechanisms and potential therapeutic targets.

**Why Each Wrong Option is Incorrect**
**Option A:** Microarray is not used for DNA sequencing, which is a different technique that involves determining the order of nucleotides in a DNA molecule. While microarray can provide information on gene expression, it does not provide a complete sequence of the genome.
**Option B:** Microarray is not used for PCR (polymerase chain reaction), which is a laboratory technique used to amplify specific DNA sequences. While PCR can be used to generate the DNA probes used in microarray analysis, the two techniques are distinct and serve different purposes.
**Option C:** Microarray is not used for Western blotting, which is a laboratory technique used to detect specific proteins in a sample. While both microarray and Western blotting can be used to study gene expression, they analyze different levels of biological information (gene vs. protein).

**Clinical Pearl / High-Yield Fact**
One key application of microarray technology is in the field of cancer research, where it can be used to identify genes that are differentially expressed in cancer cells compared to normal cells. This can provide insights into the underlying biology of cancer and potential therapeutic targets.

**Correct Answer:**
(To be completed with the actual correct option)