**Core Concept**
Tuberculosis (TB) is a bacterial infection caused by Mycobacterium tuberculosis. Resistance to anti-TB drugs is a major public health concern, as it complicates treatment and increases the risk of treatment failure and transmission. The development of resistance is primarily due to the genetic mutations in the bacteria that alter their drug targets or increase their ability to efflux drugs.

**Why the Correct Answer is Right**
Resistance to anti-TB drugs is primarily mediated by chromosomal mutations in the bacterial genome. The most common mechanism of resistance is the mutation in the rpoB gene, which codes for the beta-subunit of RNA polymerase. This mutation leads to the development of rifampicin resistance. Other mechanisms of resistance include mutations in the katG gene, which codes for the enzyme catalase-peroxidase, and the inhA gene, which codes for the enzyme enoyl-acyl carrier protein reductase. The efflux pumps, such as the Rv1258c gene, also contribute to the development of resistance.

**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect as it does not accurately describe the primary mechanism of resistance to anti-TB drugs.
**Option B:** This option is incorrect as it is not a recognized mechanism of resistance to anti-TB drugs.
**Option C:** This option is incorrect as it is a general term and does not specifically describe the mechanism of resistance to anti-TB drugs.

**Clinical Pearl / High-Yield Fact**
The development of resistance to anti-TB drugs is often due to incomplete or irregular treatment, which can lead to the selection of resistant strains. Therefore, adherence to the full treatment regimen is crucial to prevent the development of resistance.

**Correct Answer:** C. Mutations in the bacterial genome.