**Core Concept**
The active management of the third stage of labour involves the use of a uterotonic agent to reduce postpartum hemorrhage risk. **Uterotonic agents** help stimulate the uterus to contract, thereby reducing bleeding. The preferred drug and route are crucial for effective management.

**Why the Correct Answer is Right**
The most commonly recommended uterotonic agent for active management of the third stage of labour is **oxytocin**, administered via the intramuscular route. Oxytocin stimulates uterine contractions, helping to reduce bleeding and facilitate placental separation. Its use is backed by strong evidence for efficacy and safety.

**Why Each Wrong Option is Incorrect**
**Option A:** Incorrect due to lack of specificity regarding the drug and route.
**Option B:** Incorrect as it does not align with the recommended practice for active management of the third stage of labour.
**Option C:** Incorrect because, although it might be a uterotonic, it's not the preferred choice for this specific context.
**Option D:** Incorrect as it does not specify the drug and route accurately.

**Clinical Pearl / High-Yield Fact**
Remember, **oxytocin** is the first-line uterotonic agent for preventing postpartum hemorrhage during the third stage of labour, and its administration should be accompanied by other components of active management, such as controlled cord traction and uterine massage.

**Correct Answer:** D. Oxytocin intramuscularly.