**Core Concept**
Tubal ligation is a surgical procedure that involves cutting or blocking the fallopian tubes to prevent pregnancy. The procedure is often performed as a form of female sterilization. The underlying principle being tested is the relationship between tubal ligation and the risk of certain health conditions.

**Why the Correct Answer is Right**
Tubal ligation has been associated with a decreased risk of ovarian cancer. This is because the procedure involves removing a portion of the fallopian tube, which contains cells that can potentially become malignant. The removal of these cells reduces the risk of cancer development. The exact mechanism is not fully understood, but it is thought that the removal of the fallopian tube tissue may reduce the exposure of the ovaries to carcinogens.

**Why Each Wrong Option is Incorrect**
* **Option A:** There is no conclusive evidence to suggest that tubal ligation decreases the risk of endometrial cancer. In fact, some studies have suggested that tubal ligation may actually increase the risk of endometrial cancer.
* **Option B:** Tubal ligation is not known to decrease the risk of breast cancer. The relationship between tubal ligation and breast cancer risk is complex and has been the subject of much debate.
* **Option C:** Tubal ligation is not associated with a decreased risk of cervical cancer. In fact, some studies have suggested that tubal ligation may actually increase the risk of cervical cancer.

**Clinical Pearl / High-Yield Fact**
It is essential to note that while tubal ligation is associated with a decreased risk of ovarian cancer, it is not a guarantee against the development of cancer. Patients who undergo tubal ligation should still undergo regular cancer screening and follow-up.

**Correct Answer:** D. Ovarian cancer