**Core Concept**
Carbetocin is a long-acting oxytocic agent used to prevent or treat postpartum hemorrhage (PPH). It is a synthetic analogue of oxytocin with a longer duration of action, which allows for single-dose administration.

**Why the Correct Answer is Right**
Carbetocin works by stimulating the uterine muscle receptors, specifically the oxytocin receptors, to induce uterine contractions. This leads to a reduction in uterine bleeding and prevention of PPH. The recommended dose of carbetocin for PPH is 100 micrograms, administered intravenously, which provides a longer duration of action compared to oxytocin.

**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect as there is no standard dose of carbetocin used for PPH that is lower than 100 micrograms.
**Option B:** This option is incorrect as carbetocin is not typically administered subcutaneously for PPH.
**Option C:** This option is incorrect as the dose of carbetocin used for PPH is not higher than 100 micrograms.

**Clinical Pearl / High-Yield Fact**
Carbetocin is a useful option for preventing PPH in patients undergoing cesarean delivery, as it provides a longer duration of action compared to oxytocin, reducing the need for repeated doses.

**Correct Answer: D. 100 micrograms**