Okay, let's tackle this question about anti-tubercular drugs not given in children under 6 years old. First, I need to recall which drugs have age restrictions. The core concept here is the safety profile of anti-TB medications in pediatric populations, particularly those under six.

The correct answer is likely Pyrazinamide. Wait, no, maybe it's another drug. Let me think. I remember that Pyrazinamide is generally safe in children, but there's another drug that's problematic. Oh right, Ethambutol. But wait, Ethambutol's main issue is optic neuropathy, which is more of a concern in adults. Wait, no, maybe it's Rifampin? No, Rifampin is used in children. Oh, wait, there's another one. Oh! Ciprofloxacin and other fluoroquinolones are contraindicated in children because they can cause cartilage damage. But TB treatment in children usually avoids fluoroquinolones. However, the question is about anti-tubercular drugs not given in children under 6. Let me check the options again. The options are missing letters, but the correct answer is probably C. Cycloserine. No, Cycloserine is used in multidrug-resistant TB and has neuropsychiatric side effects, but it's not specifically contraindicated in young children. Wait, another one: Streptomycin? It's an aminoglycoside, which can cause ototoxicity and nephrotoxicity, but it's used in certain cases. Hmm. Wait, the answer I remember is Ethambutol. But why? Because of optic neuropathy. However, in children under 6, they don't use Ethambutol because of the risk of optic neuropathy, especially in those under 5. So the answer is Ethambutol. But wait, some sources say that Ethambutol is not recommended in children under 5 or 6 years. So the correct answer would be Ethambutol. Let me confirm: Ethambutol is contraindicated in children under 5 years due to the risk of optic neuropathy. So the answer is Ethambutol. Therefore, the correct answer is C. Ethambutol. But the options are labeled A to D without letters assigned. The user didn't provide the options, but the correct answer is Ethambutol. So the explanation would focus on why Ethambutol is not given in children under 6. The other options would be other drugs like Rifampin, Isoniazid, Pyrazinamide, which are safe. The clinical pearl is that Ethambutol is avoided in young children due to optic neuropathy risk, which is a high-yield fact for exams.

**Core Concept**
This question tests knowledge of pediatric-specific contraindications in antitubercular therapy. Ethambutol is contraindicated in children < 5–6 years due to its association with optic neuropathy, which is irreversible and difficult to detect in young children. **Why the Correct Answer is Right** Ethambutol is an antimycobacterial drug used in multidrug-resistant TB regimens. Its primary adverse effect is optic neuropathy (dose-dependent, reversible in adults but not in children). In children <

✓ Correct Answer: A. Ethambutol