Could you explain the answer? 16/ A group of scientists believe they have found a single dose universal influenza vaccine that is resistant to antigenic drift and antigenic shift. The FDA grants them a phase 1 trial to test the safety of this new vac- cination. The incidence of influenza is shown in the following table: Annual Incidence of Influenza After Receiving 1 Dose of Universal Flu Vaccine Patient 1 Patient 2 Patient 3 Patient 4 Patient 5 Patient 6 0 1 2 3 4 5 Influenza diagnosis & Death Attrition What is the incidence density of Influenza after receiving the experimental influenza vaccine? A. 0.13 cases/person-year B. 0.25 cases/person-year C. 0.5 D. 3 E. 4