Okay, let's tackle this question about the mechanism of action of streptomycin. First, I need to recall what streptomycin does. It's an aminoglycoside antibiotic, right? Aminoglycosides like gentamicin and tobramycin are similar. Their main target is bacterial protein synthesis.

So, protein synthesis in bacteria involves ribosomes. Streptomycin affects the 30S ribosomal subunit. I remember that other aminoglycosides also bind to the 30S subunit, causing misreading of mRNA. This leads to the production of faulty proteins, which the bacteria can't survive.

Wait, the options might include other ribosomal subunits or different mechanisms. Let's think about the other antibiotics. For example, chloramphenicol and erythromycin target the 50S subunit, inhibiting peptidyl transferase. Clindamycin also affects the 50S. So if an option says 50S, that's wrong for streptomycin.

Another possible distractor could be about inhibiting cell wall synthesis, which is what beta-lactams like penicillin do. Or maybe inhibiting DNA gyrase, which is how fluoroquinolones work. So if any options mention cell wall or DNA gyrase, they're incorrect here.

Also, streptomycin is known to cause irreversible binding to the 30S subunit, which is why it's bactericidal. Once it binds, the ribosome can't function properly, leading to the bacteria's death.

The clinical pearl here is that aminoglycosides like streptomycin all target the 30S ribosomal subunit. This is a key point for exams. Students might confuse them with other antibiotics that target different subunits. Also, knowing that streptomycin is used in certain infections, like tuberculosis, but the question is specifically about the mechanism.

So the correct answer should be B (if B is the option that says "Inhibits bacterial protein synthesis by binding to the 30S ribosomal subunit"). The other options would be incorrect if they mention 50S, cell wall, DNA gyrase, or something else. Each wrong option needs a brief explanation. For example, if an option says 50S, I can explain that aminoglycosides target 30S, not 50S. If another says cell wall, then mention that's beta-lactams.

**Core Concept**
Streptomycin is an aminoglycoside antibiotic that interferes with bacterial protein synthesis by binding to the **30S ribosomal subunit**, inducing misreading of mRNA and inhibiting translocation. This leads to the production of nonfunctional proteins and eventual bacterial cell death.

**Why the Correct Answer is Right**
Streptomycin binds to the **16S rRNA** of the 30S ribosomal subunit, altering its conformation. This prevents the ribosome from accurately reading mRNA codons, causing **irreversible inhibition of protein synthesis**. Unlike other antibiotics (e.g., tetracyclines), streptomycin also blocks translocation, preventing peptide chain elongation. Its bactericidal effect is due to irreversible ribosome binding.

**Why Each Wrong Option is Incorrect

✓ Correct Answer: A. Inhibition of translation