**Core Concept**
The development of benign prostatic hyperplasia (BPH) is a complex process involving the growth and proliferation of prostate gland cells, particularly in the periurethral zone. This growth can lead to an enlargement of the prostate gland, which can cause urinary symptoms.

**Why the Correct Answer is Right**
The most common lobe involved in BPH is the transition zone, which is the periurethral region of the prostate gland. The transition zone is composed of glandular and fibromuscular tissue, and its growth is thought to be driven by an increase in androgen-stimulated growth factors, such as dihydrotestosterone (DHT). The transition zone is the thinnest part of the prostate gland and is surrounded by the prostatic urethra, making it more susceptible to enlargement and subsequent urinary obstruction.

**Why Each Wrong Option is Incorrect**
* **Option A:** This option is incorrect because the transition zone, not the peripheral zone, is the most common lobe involved in BPH.
* **Option B:** This option is incorrect because the anterior lobe of the prostate gland is not typically involved in BPH.
* **Option C:** This option is incorrect because the posterior lobe of the prostate gland is not typically involved in BPH.

**Clinical Pearl / High-Yield Fact**
The transition zone of the prostate gland is the thinnest part of the gland and is most susceptible to enlargement in BPH, making it a key area to consider in the diagnosis and management of urinary symptoms.

**Correct Answer: C. Posterior lobe is not commonly involved.