**Core Concept**
Sarcoma botryoides, also known as embryonal rhabdomyosarcoma, is a rare type of cancer that primarily affects the genitourinary tract in young children. It is characterized by its grape-like appearance on histopathology, hence the name "botryoides," meaning "grape-like."

**Why the Correct Answer is Right**
Sarcoma botryoides typically presents as a polypoid mass in the vagina or bladder of infants and young children. The tumor arises from the embryonal cells of the bladder or vagina and rapidly grows, leading to obstructive symptoms such as urinary retention or constipation. The histopathological appearance of the tumor is characterized by a grape-like cluster of cells, with a loose, myxoid stroma.

**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because Sarcoma botryoides is not typically associated with the gastrointestinal tract.
**Option B:** This option is incorrect because Sarcoma botryoides is not commonly seen in adults.
**Option C:** This option is incorrect because Sarcoma botryoides is not typically characterized by a firm, hard mass.

**Clinical Pearl / High-Yield Fact**
Sarcoma botryoides is a highly malignant tumor that requires prompt surgical intervention and adjuvant chemotherapy to improve survival rates.

**Correct Answer:** D.