**Core Concept**
The question describes a case of urethritis, a type of infection affecting the urethra. The gram-negative microbe responsible for this condition is likely Neisseria gonorrhoeae, a bacterium that causes gonorrhea. Gonorrhea is a sexually transmitted infection (STI) that can lead to symptoms such as painful urination and discharge.

**Why the Correct Answer is Right**
Neisseria gonorrhoeae is primarily transmitted through sexual contact, making option C the most likely mode of acquisition. This bacterium can infect both men and women, causing urethritis in men and cervicitis in women. The transmission of gonorrhea occurs during vaginal, anal, or oral sex with an infected partner. The bacterium can also be transmitted from mother to baby during childbirth.

**Why Each Wrong Option is Incorrect**
* **Option A:** While water can be contaminated with various bacteria, it is not a common mode of transmission for gonorrhea.
* **Option B:** Fecal-oral transmission is not a typical mode of transmission for gonorrhea.
* **Option D:** Contaminated food and water are not typical sources of gonorrhea.

**Clinical Pearl / High-Yield Fact**
Gonorrhea can lead to complications such as pelvic inflammatory disease (PID) in women and epididymitis in men if left untreated.

**Correct Answer:** C.