The correct answer is choice A. Shortness of breath and chest pain are signs of pulmonary embolism (PE), which is a life-threatening complication of deep vein thrombosis (DVT). DVT is a type of blood clot that can occur in the legs or arms, especially during pregnancy and postpartum. PE happens when a blood clot breaks off and travels to the lungs, blocking blood flow.

Choice B is wrong because nausea and vomiting are not specific signs of thromboembolism.

They can be caused by many other conditions, such as morning sickness, food poisoning, or medication side effects.

Choice C is wrong because headache and blurred vision are not typical signs of thromboembolism.

They can be associated with other pregnancy complications, such as preeclampsia or eclampsia.

Choice D is wrong because fever and chills are not common signs of thromboembolism.

They can indicate an infection or inflammation, such as mastitis or endometritis.

Pregnant women have a higher risk of developing DVT and PE because of hormonal changes, increased blood clotting factors, reduced blood flow to the legs, and other factors. The risk is even higher after a cesarean delivery.

Therefore, it is important to know the signs and symptoms of thromboembolism and seek immediate medical attention if they occur. Thromboembolism can be prevented and treated with anticoagulant medications, compression stockings, and physical activity.