**Core Concept**
In obstetrics, the presence of an abortus (products of conception after a miscarriage or abortion) in the uterus, combined with a dilated open os (cervix), indicates a specific clinical scenario. This presentation is often associated with a condition where the cervix has dilated prematurely due to uterine distension or other factors.

**Why the Correct Answer is Right**
The correct answer is suggestive of a condition known as **Inevitable Abortion**. Inevitable abortion occurs when the cervix has dilated and the os is open, but the fetus has not yet been expelled. This is often due to a spontaneous abortion, where the cervix dilates prematurely, allowing the products of conception to pass through. The presence of an abortus in the uterus, along with a dilated open os, is a hallmark of this condition.

**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because it does not accurately describe the clinical presentation of an inevitable abortion. A missed abortion, on the other hand, occurs when the fetus has died but remains in the uterus, and the cervix has not yet dilated.

**Option B:** This option is incorrect because it does not accurately describe the clinical presentation of an inevitable abortion. A threatened abortion occurs when there is vaginal bleeding or mild uterine contractions, but the cervix has not yet dilated.

**Option C:** This option is incorrect because it does not accurately describe the clinical presentation of an inevitable abortion. A complete abortion occurs when the fetus has been expelled from the uterus, and the cervix has returned to its pre-pregnancy state.

**Clinical Pearl / High-Yield Fact**
In obstetrics, it is essential to differentiate between inevitable abortion and other types of spontaneous abortion. A thorough history and physical examination, combined with imaging studies, can help diagnose and manage this condition.

**Correct Answer:** C. Complete abortion