**Core Concept**
Prostatic carcinoma, also known as prostate cancer, is a malignant neoplasm originating from the prostate gland. The prostate gland is a male reproductive organ responsible for secreting fluids that make up semen.

**Why the Correct Answer is Right**
Prostatic carcinoma commonly arises from the glandular epithelium of the prostate gland, specifically from the peripheral zone. This is because the peripheral zone accounts for approximately 70-80% of the glandular tissue in the prostate, making it a more susceptible area for malignant transformation. The glandular epithelium in the peripheral zone is composed of prostatic glands and ducts that secrete prostatic fluid.

**Why Each Wrong Option is Incorrect**
**Option A:** The transition zone is a common site for benign prostatic hyperplasia (BPH), not prostatic carcinoma.

**Option B:** The seminal vesicles are separate organs located near the prostate gland and are not a common site for prostatic carcinoma.

**Option C:** The prostatic urethra is a passage through the prostate gland but is not a common site for prostatic carcinoma.

**Clinical Pearl / High-Yield Fact**
It's essential to remember that the majority of prostatic carcinomas arise from the glandular epithelium of the peripheral zone, which is why imaging studies like ultrasound and MRI are often used to target this area for biopsy.

**Correct Answer:** C.