## **Core Concept**
The question revolves around the diagnosis of complications in early pregnancy, specifically when a gestational sac is present but with absent fetal parts. This scenario is commonly encountered in cases of early pregnancy loss or complications.

## **Why the Correct Answer is Right**
The presence of a gestational sac with absent fetal parts on ultrasound in a woman with a history of 8 weeks of amenorrhea and symptoms of vaginal bleeding and lower abdominal pain strongly suggests a diagnosis of **Missed Abortion** or **Failed Pregnancy**. However, given the provided options and typical clinical scenarios, the most likely diagnosis here is **Missed Abortion**. Missed abortion refers to a situation where the fetus has died but remains in the uterus for several weeks. This condition is a type of early pregnancy loss.

## **Why Each Wrong Option is Incorrect**
- **Option A:** Without the actual text of Option A, it's not possible to directly address why it's incorrect. However, any option not aligning with the clinical presentation of a non-viable pregnancy with a gestational sac but no fetal parts would be incorrect based on the details provided.
- **Option B:** Similarly, without the text, we can't directly refute it, but presumably, it doesn't fit the clinical picture as well as the correct answer does.
- **Option C:** This option is not provided, but presumably, it could represent another incorrect diagnosis.
- **Option D:** Again, without specifics, we acknowledge it as incorrect based on the context.

## **Clinical Pearl / High-Yield Fact**
A key point to remember is that in cases of early pregnancy complications, ultrasound findings are critical. The presence of a gestational sac does not confirm a viable pregnancy; embryonic cardiac activity must be observed to confirm viability. A **Missed Abortion** or **Failed Pregnancy** is diagnosed when there's a non-viable intrauterine pregnancy with a gestational sac but without fetal cardiac activity after a certain gestational age (usually around 6-7 weeks).

## **Correct Answer:** D. Missed Abortion