**Blighted Ovary Explained**

**Core Concept**
A blighted ovum, also known as an anembryonic pregnancy, is a type of early pregnancy loss where the embryo fails to develop, resulting in a non-viable pregnancy. This condition is characterized by the presence of a gestational sac without an embryo. The exact cause of blighted ovum is often unknown.

**Why the Correct Answer is Right**
The correct answer is related to the definition of a blighted ovum. In a blighted ovum, the embryo fails to develop, and the gestational sac is present without an embryo. This condition occurs due to an issue with embryonic development, often related to chromosomal abnormalities or other genetic factors. The presence of a gestational sac without an embryo is a key diagnostic feature of a blighted ovum.

**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because a blighted ovum is not the same as a missed abortion, which occurs when the embryo has died but is still present within the uterus.
**Option B:** This option is incorrect because a blighted ovum is not the same as a molar pregnancy, which is a type of gestational trophoblastic disease characterized by the abnormal growth of trophoblastic tissue.
**Option C:** This option is incorrect because a blighted ovum is not the same as an ectopic pregnancy, which occurs when the embryo implants outside the uterus, typically in the fallopian tube.

**Clinical Pearl / High-Yield Fact**
A blighted ovum is often diagnosed through ultrasound, which shows a gestational sac without an embryo. It's essential to note that a blighted ovum can be a sign of underlying fertility issues or genetic problems, and patients may benefit from further evaluation and counseling.

**Correct Answer: B. Blighted ovum**