**Core Concept**
The underlying principle being tested is the identification of a probable causative agent for a patient presenting with bilateral lymphadenopathy, which is tender on palpation, and a history of sexual contact. This scenario suggests a sexually transmitted infection (STI). The patient's profession as a truck driver may increase his risk for such infections due to mobility and potential for multiple sexual contacts.

**Why the Correct Answer is Right**
Given the context of sexual contact and the symptom of tender bilateral lymphadenopathy, the most likely diagnosis is lymphogranuloma venereum (LGV), which is caused by **Chlamydia trachomatis** serovars L1, L2, or L3. LGV is characterized by its ability to cause lymphadenopathy, which is often tender, and its association with sexual transmission.

**Why Each Wrong Option is Incorrect**
**Option A:** Without the specific option provided, it's challenging to give a precise reason for its incorrectness, but if it were a common STI not typically associated with lymphadenopathy, such as gonorrhea, it would be incorrect.
**Option B:** Similarly, without the specific option, if it were an agent not commonly associated with sexual transmission or lymphadenopathy, it would be incorrect.
**Option C:** If this option were an agent like **Treponema pallidum** (syphilis), while syphilis can cause lymphadenopathy, the context provided (tender lymphadenopathy and specific mention of sexual contact) more strongly suggests LGV.
**Option D:** If this option were an agent not associated with STIs or lymphadenopathy, it would clearly be incorrect.

**Clinical Pearl / High-Yield Fact**
A key point to remember is that lymphogranuloma venereum (LGV) is a significant cause of lymphadenopathy in the context of sexual transmission, particularly in individuals with high-risk sexual behaviors. The tender nature of the lymphadenopathy is a distinguishing feature.

**Correct Answer:** Correct Answer: D. Chlamydia trachomatis.