**Core Concept**
Streptogramins are a class of antibiotics that inhibit bacterial protein synthesis by binding to the 50S ribosomal subunit. They are composed of two components, a streptogramin B (SB) and a streptogramin A (SA), which act synergistically to exert their bactericidal effect.

**Why the Correct Answer is Right**
Streptogramins work by binding to the 50S ribosomal subunit, which is responsible for peptide bond formation. The SA component binds to the 50S ribosomal subunit, stabilizing the complex and preventing the release of the nascent peptide chain. The SB component then binds to a different region of the 50S ribosomal subunit, further stabilizing the complex and ultimately leading to the inhibition of protein synthesis. This synergistic action of the two components is what makes streptogramins effective against a wide range of bacteria.

**Why Each Wrong Option is Incorrect**
**Option A:** Streptogramins are a class of antibiotics that inhibit bacterial DNA synthesis. (This statement is incorrect because streptogramins inhibit protein synthesis, not DNA synthesis.)
**Option B:** Streptogramins are composed of only one component, which is sufficient for their bactericidal effect. (This statement is incorrect because streptogramins require the synergistic action of both SB and SA components to exert their effect.)

**Clinical Pearl / High-Yield Fact**
Streptogramins are often used in combination with other antibiotics to treat serious infections, such as skin and soft tissue infections, and respiratory tract infections.

**Correct Answer: A. Streptogramins are a class of antibiotics that inhibit bacterial DNA synthesis.**