**Core Concept**
The treatment of sex partners is a crucial aspect of managing sexually transmitted infections (STIs) to prevent transmission and re-infection. This approach is grounded in the concept of syndromic management, which involves treating a combination of symptoms and signs to manage an STI, rather than relying on laboratory confirmation.

**Why the Correct Answer is Right**
Treatment of sex partners is essential for several STIs, including gonorrhea, chlamydia, and syphilis, as these infections can be asymptomatic in women and may not be diagnosed without screening. For example, in gonorrhea, the Centers for Disease Control and Prevention (CDC) recommend that all sex partners of individuals with gonorrhea be treated empirically with antibiotics to prevent re-infection and transmission. This approach is particularly important for infections that can lead to serious complications, such as pelvic inflammatory disease (PID) in women.

**Why Each Wrong Option is Incorrect**
**Option A:** While this option might seem correct, it is not a universally applicable exception.
**Option B:** This is incorrect because treatment of sex partners is indeed required for STIs like chlamydia, which is a common cause of PID.
**Option C:** This is also incorrect because treatment of sex partners is recommended for syphilis, a bacterial infection that can cause serious complications if left untreated.

**Clinical Pearl / High-Yield Fact**
The CDC recommends that all sex partners of individuals with gonorrhea be treated empirically with antibiotics, regardless of symptoms, to prevent re-infection and transmission.

**Correct Answer: D.**