Final answer:
Immobility is the factor that places the postpartum client at risk for thromboembolism.
Step-by-step explanation:
The factor that places the postpartum client at risk for thromboembolism is c) Immobility. Immobility after childbirth can lead to blood clots forming in the legs, which can then travel to the lungs causing a pulmonary embolism. It is important for postpartum clients to move and exercise regularly to help prevent thromboembolism.