**Core Concept**
Beta-hCG (human chorionic gonadotropin) is a hormone produced during pregnancy that is used as a marker for fetal development and placental function. Monitoring beta-hCG levels is essential in managing pregnancies, particularly in cases of suspected ectopic pregnancy or molar pregnancy.

**Why the Correct Answer is Right**
Beta-hCG levels typically rise exponentially during early pregnancy, peaking around 10-12 weeks of gestation. Monitoring beta-hCG levels can help detect abnormal pregnancies, such as ectopic pregnancies, where the hormone levels may not increase or may decrease. In cases of molar pregnancy, beta-hCG levels are often significantly elevated. Additionally, beta-hCG levels can be used to evaluate the effectiveness of treatments for abnormal pregnancies.

**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because beta-hCG monitoring is not primarily used for managing hypertension in pregnancy. While beta-hCG levels may be elevated in some cases of preeclampsia, monitoring of beta-hCG is not a standard practice for managing hypertension.

**Option B:** This option is incorrect because beta-hCG monitoring is not directly used for managing gestational diabetes. While beta-hCG levels may be elevated in some cases of gestational diabetes, monitoring of beta-hCG is not a standard practice for managing the condition.

**Option C:** This option is incorrect because beta-hCG monitoring is not primarily used for managing postpartum hemorrhage. While beta-hCG levels may be elevated in some cases of postpartum hemorrhage, monitoring of beta-hCG is not a standard practice for managing the condition.

**Clinical Pearl / High-Yield Fact**
A key clinical correlation to remember is that beta-hCG levels can be used to differentiate between a normal intrauterine pregnancy and an ectopic pregnancy. A beta-hCG level that is not increasing or is decreasing may indicate an ectopic pregnancy.

**Correct Answer: C. Molar pregnancy. Monitoring of beta-hCG is useful in management of molar pregnancy.**