**Core Concept**
Goodsall's rule is a clinical guideline used to predict the likelihood of a skin lesion or abscess forming a fistula with the nearby bowel. This rule is based on the anatomical relationship between the skin and the bowel, specifically the position of the anal glands.

**Why the Correct Answer is Right**
Goodsall's rule states that if the anterior midline of an anal skin tag or abscess is within 3-4 cm of the anal verge, it is more likely to track down to the anal canal and form a fistula-in-ano. This is because the anal glands, which are prone to infection and abscess formation, are located in the anal submucosa and are more likely to drain into the anal canal when the skin lesion is located in this area. The anal glands are lined by mucous glands and are prone to obstruction, leading to infection and abscess formation.

**Why Each Wrong Option is Incorrect**
**Option A:** Goodsall's rule is not applicable to lesions located on the posterior midline of the anus.
**Option B:** Goodsall's rule is not a guideline for predicting the likelihood of a skin lesion or abscess forming a fistula with the nearby bladder.
**Option C:** Goodsall's rule is not a guideline for predicting the likelihood of a skin lesion or abscess forming a fistula with the nearby urethra.

**Clinical Pearl / High-Yield Fact**
Goodsall's rule is a useful clinical guideline for predicting the likelihood of a skin lesion or abscess forming a fistula with the nearby bowel, but it is not a substitute for a thorough clinical examination and diagnostic workup.

**Correct Answer:** C.