Final answer:
The recommended course of action is to immediately admit the child to the hospital due to symptoms indicating a serious complication of sickle cell anemia.
Step-by-step explanation:
The most conservative course of action for a 4-year-old child with sickle cell anemia who is presenting with fast breathing, coughing, and a high temperature of 104°F is D) Admit child to hospital. These symptoms indicate a potential acute chest syndrome or another serious complication of sickle cell anemia, which requires immediate medical attention.
Waiting for an office appointment or prescribing medication without proper assessment could put the child at risk. Hospital admission ensures that the child will receive immediate care, including thorough diagnostic evaluations such as a hematocrit, white blood cell count, and differential, as well as necessary treatments like oxygen, fluids, and possibly antibiotics.