**Core Concept**
Breast cancer is a common malignancy that can metastasize to various sites, including the orbit. Intraorbital metastasis, also known as orbital metastasis, occurs when cancer cells from a primary tumor spread to the orbit, leading to various symptoms and complications.

**Why the Correct Answer is Right**
Breast cancer is the most common cause of intraorbital metastasis in females due to its high incidence and propensity for metastasis. The cancer cells from the breast can spread to the orbit through the bloodstream or lymphatic system, leading to the formation of a metastatic tumor. The most common symptom of intraorbital metastasis is proptosis (bulging of the eye), which is caused by the accumulation of tumor cells in the orbital tissues.

**Why Each Wrong Option is Incorrect**
* **Option A:** While lung cancer is a common malignancy, it is less likely to cause intraorbital metastasis compared to breast cancer. Lung cancer is more likely to metastasize to the brain, bones, or liver.
* **Option B:** Colorectal cancer is a common malignancy, but it is less likely to cause intraorbital metastasis. Colorectal cancer is more likely to metastasize to the liver, lungs, or peritoneum.
* **Option D:** Ovarian cancer is a common malignancy in females, but it is less likely to cause intraorbital metastasis. Ovarian cancer is more likely to metastasize to the peritoneum, liver, or lungs.

**Clinical Pearl / High-Yield Fact**
Intraorbital metastasis is a rare but serious complication of cancer, and it can cause significant morbidity and mortality. Breast cancer is the most common cause of intraorbital metastasis in females, and it is essential for clinicians to be aware of this potential complication when managing patients with breast cancer.

**Correct Answer:** C.