**Core Concept**
Multi-drug resistant tuberculosis (MDR-TB) is a significant public health concern due to the increasing prevalence of strains resistant to first-line antitubercular drugs. The introduction of new drugs is crucial to combat MDR-TB. The pharmacological principle being tested here involves the development of novel antitubercular agents.

**Why the Correct Answer is Right**
Delamanid (Bedaquiline) is a diarylquinoline antibiotic that inhibits the proton pump in Mycobacterium tuberculosis, disrupting ATP synthesis and subsequently killing the bacteria. It is specifically designed to target the mycobacterial ATP synthase, an essential enzyme for energy production. Delamanid has been approved for the treatment of MDR-TB, especially in cases where other treatments have failed.

**Why Each Wrong Option is Incorrect**
* **Option A:** Isoniazid is a first-line antitubercular drug used to treat TB, but it is not effective against MDR-TB strains.
* **Option B:** Rifampicin is another first-line antitubercular drug, but its effectiveness is compromised in MDR-TB due to resistance.
* **Option D:** Pyrazinamide is a first-line antitubercular drug used in combination with isoniazid and rifampicin, but it is not a new drug for MDR-TB treatment.

**Clinical Pearl / High-Yield Fact**
Delamanid (Bedaquiline) has been shown to have a significant improvement in outcomes for patients with MDR-TB, particularly in those with extensively drug-resistant TB (XDR-TB). It is essential to note that delamanid should be used under strict supervision due to its potential side effects and interactions.

**Correct Answer: C. Delamanid (Bedaquiline)**