**Core Concept:** The question is asking about an anti-tuberculosis drug that can cause flu-like symptoms as a side effect. Anti-TB drugs play a crucial role in treating Mycobacterium tuberculosis infections, which cause Tuberculosis (TB).

**Why the Correct Answer is Right:** Isoniazid is an anti-TB drug that belongs to the category of first-line drugs. It is an inhibitor of mycobacterial pyruvate dehydrogenase complex, which is essential for the growth of TB bacteria. This inhibition leads to the production of toxic intermediates that cause various side effects, including flu-like symptoms like fever and chills.

**Why Each Wrong Option is Incorrect:**

A. Rifampicin is another first-line anti-TB drug that inhibits RNA synthesis in Mycobacterium tuberculosis. However, it does not cause flu-like symptoms as its mode of action is not directly related to pyruvate dehydrogenase complex inhibition or production of toxic intermediates.

B. Ethambutol is an anti-TB drug that targets mycolic acid synthesis in Mycobacterium tuberculosis. Although it has side effects like optic neuritis, it does not cause flu-like symptoms due to its specific mechanism of action.

C. Pyrazinamide is another first-line anti-TB drug that inhibits mycobacterial pyruvate dehydrogenase complex, just like isoniazid. However, its side effects usually do not include flu-like symptoms as the mechanism of action is similar to isoniazid but the side effects are generally milder.

D. Streptomycin is an aminoglycoside antibiotic that targets the 16S rRNA synthesis in Mycobacterium tuberculosis. Its side effects are usually related to ear and kidney damage, not flu-like symptoms.

**Clinical Pearl:** While all anti-TB drugs have some side effects, the specific mechanism of action and toxic intermediates produced by isoniazid make it particularly likely to cause flu-like symptoms compared to other anti-TB drugs.

**Correct Answer:** D. Streptomycin

**Why Each Wrong Option is Incorrect:**

A. Rifampicin and Ethambutol are first-line anti-TB drugs, but they do not cause flu-like symptoms due to their specific mechanisms of action and side effect profiles.

B. Pyrazinamide is a first-line anti-TB drug that causes side effects related to its mechanism of action, but flu-like symptoms are not typically reported as a side effect.

C. Isoniazid, as explained above, is associated with flu-like symptoms due to its mechanism of action and toxic intermediates production.

**Clinical Pearls:**

1. Anti-TB drugs are essential in treating TB infections, but understanding their side effects is crucial for effective treatment and patient management.
2. Clinicians should be aware of the specific side effects associated with different drugs, as this knowledge can guide treatment decisions and patient counselling.