Final answer:
Erythromycin is the antibiotic that meets all the given criteria: it targets protein synthesis, has a large lactone ring, attaches to the ribosomal subunit, prevents translocation, has a narrow spectrum, low toxicity, and is readily absorbed.
Step-by-step explanation:
Based on the given information, the antibiotic that targets protein synthesis with a large lactone ring, attaches to the ribosomal subunit, prevents translocation, has a narrow spectrum, low toxicity, and is readily absorbed is Erythromycin. Erythromycin is a macrolide antibiotic that binds to the 50S ribosomal subunit, inhibiting protein synthesis in sensitive microorganisms. It specifically prevents translocation, which is the movement of the ribosome along the mRNA during translation.