**Core Concept**
The male urethra is a tube-like structure that extends from the bladder to the external urethral orifice, allowing the passage of urine. Its length is an essential anatomical consideration in urological procedures and surgeries.

**Why the Correct Answer is Right**
The male urethra is approximately 20 cm in length, consisting of three distinct segments: the prostatic urethra, membranous urethra, and penile (or spongy) urethra. The prostatic urethra passes through the prostate gland, while the membranous urethra is a short, rigid segment surrounded by the urethral sphincter. The penile urethra then traverses the corpus spongiosum of the penis, terminating at the external urethral orifice. This distinct anatomy is crucial for understanding urethral injuries and surgical approaches.

**Why Each Wrong Option is Incorrect**
**Option A:** 15 cm - This length is too short, as the membranous urethra alone measures approximately 1-2 cm, and the prostatic urethra is longer than this value.
**Option B:** 25 cm - This length is too long, as the penile urethra is approximately 15-17 cm in length, and the prostatic and membranous segments do not add enough length to reach this value.
**Option C:** 10 cm - This length is too short, as it does not account for the prostatic or penile urethra segments.

**Clinical Pearl / High-Yield Fact**
The male urethra's unique anatomy makes it susceptible to injuries, particularly during pelvic fractures or catheterization. Understanding the urethral segments is essential for diagnosing and managing urethral trauma.

**Correct Answer: D. 20 cm**