**Core Concept**
The patient's presentation suggests a severe and acute complication of pregnancy, characterized by a sudden onset of shock, cyanosis, respiratory distress, and pulmonary edema. This condition is a result of placental abruption, where the placenta separates from the uterus, leading to hemorrhage and shock.

**Why the Correct Answer is Right**
The patient's symptoms, such as strong labour pains followed by shock, cyanosis, respiratory disturbance, and pulmonary edema, are indicative of amniotic fluid embolism (AFE). AFE occurs when amniotic fluid enters the maternal circulation, triggering a severe inflammatory response, coagulopathy, and hypoxia. This leads to acute respiratory distress syndrome (ARDS), cardiac arrest, and ultimately, shock. The mechanism involves the activation of inflammatory cells, release of cytokines, and consumption of coagulation factors, resulting in disseminated intravascular coagulation (DIC).

**Why Each Wrong Option is Incorrect**
* **Option A:** Placental abruption is a possible cause of shock and labour pains but does not typically present with respiratory distress and pulmonary edema as primary symptoms.
* **Option B:** Postpartum hemorrhage can cause shock and hypovolemia but is not directly associated with respiratory distress and pulmonary edema.
* **Option C:** Eclampsia can present with seizures and hypertension but does not typically cause sudden onset of shock, cyanosis, and respiratory distress.

**Clinical Pearl / High-Yield Fact**
Amniotic fluid embolism is a leading cause of maternal mortality, with a reported incidence of 1 in 30,000 to 1 in 80,000 deliveries. Prompt recognition and management of AFE are critical, as it often presents with non-specific symptoms and can progress rapidly to fatal outcomes.

**Correct Answer:** C.