Which structural characteristic of bacterial ribosomes primarily enables selective toxicity of many protein synthesis inhibitors?

Bacterial ribosomes exist in a membrane-bound organelle and therefore are isolated from host ribosomes, allowing drugs to target them without affecting host translation machinery in the cytosol, which explains selective toxicity.

They operate at a different pH optimum than eukaryotic ribosomes and drugs selectively alter local pH around bacterial ribosomes to block protein synthesis while leaving human ribosomes unaffected.

They are 70S ribosomes made of distinct 30S and 50S subunits with rRNA and protein sequences sufficiently different from eukaryotic 80S ribosomes.

Bacterial ribosomes are composed of DNA rather than RNA and protein, a fundamental difference that antimicrobials exploit to inhibit bacterial protein synthesis without harming eukaryotic cells.