## **Core Concept**
The question tests knowledge of antitubercular agents and their side effect profiles. Antitubercular agents can cause a variety of side effects, and some are known for causing specific syndromes. The correct answer can be deduced by recalling which antitubercular agent is commonly associated with flu-like symptoms, respiratory issues, cutaneous reactions, and gastrointestinal symptoms.

## **Why the Correct Answer is Right**
The correct answer, **Pyrazinamide (PZA)**, is associated with several side effects, including hepatotoxicity, arthralgias, and hyperuricemia. However, **Rifampicin** is well-known for causing a flu-like syndrome, which includes symptoms such as fever, chills, and myalgias. It can also cause a cutaneous syndrome (rash), respiratory issues, and gastrointestinal symptoms, aligning with the description provided. Rifampicin works by inhibiting RNA synthesis in Mycobacterium tuberculosis.

## **Why Each Wrong Option is Incorrect**
- **Option A: Isoniazid** is primarily associated with hepatotoxicity, peripheral neuropathy, and pyridoxine deficiency but not commonly with the specific constellation of flu syndrome, respiratory syndrome, cutaneous syndrome, and abdominal syndrome as described.
- **Option B: Pyrazinamide (PZA)** can cause hepatotoxicity and arthralgias but is less commonly associated with the broad spectrum of syndromes mentioned.
- **Option D: Ethambutol** is known for causing optic neuritis leading to visual disturbances but is not typically associated with the syndromes listed.

## **Clinical Pearl / High-Yield Fact**
A key point to remember is that **Rifampicin** can cause a significant drug interaction with oral contraceptives, warfarin, and several other drugs due to its enzyme-inducing properties. Clinicians must be cautious when co-prescribing these medications.

## **Correct Answer Line**
**Correct Answer: C. Rifampicin.**