名词解释：病因分值（etiologic fraction，EF）

The mast common etiologic factor of DIC is () A: Infection B: Leukemia C: Obstetric disease D: Malignancy E: Extensive burns

A 20-year-old man suddenly develops fever, headache, pain behind her eyes, severe joint, bone, and muscle pain, and a maculopapular rash. He was diagnosed as Dengue fever. Control of the etiologic agent, could be possible by eradication of which of the following? A: Birds B: Fleas C: Horses D: Mosquitoes E: ticks