**Core Concept**
The couple's inability to conceive despite normal wife's tests and unprotected intercourse suggests a male factor infertility. The semen analysis reveals azoospermia (sperm count of 0), low semen volume, and the absence of fructose, which are indicative of a possible blockage in the reproductive tract.

**Why the Correct Answer is Right**
The absence of fructose in the semen suggests a blockage in the seminal vesicles, which are responsible for producing fructose, a primary energy source for sperm. This, combined with azoospermia, points towards a possible obstruction in the epididymis or vas deferens, which could be causing the sperm to be trapped and preventing their release. The correct next step would be to investigate this further.

**Why Each Wrong Option is Incorrect**
**Option A:** Hormonal evaluation would not directly address the issue of azoospermia and the absence of fructose in the semen.

**Option B:** Ultrasound would be useful in evaluating the testes and epididymis but may not provide a definitive diagnosis of the blockage.

**Option C:** Sperm culture is not indicated in this scenario as there are no sperm present.

**Option D:** Semen culture may be useful in cases of infection but is not the next best step in this scenario.

**Clinical Pearl / High-Yield Fact**
In cases of azoospermia, it's essential to investigate for possible blockages in the reproductive tract, as this can be a treatable cause of infertility.

**Correct Answer:** D. Semen culture