A Patient Showing Signs of Pneumonia Is Admitted to a Hospital

A patient showing signs of pneumonia is admitted to a hospital where tests indicate he has highly infectious M. tuberculosis. He has had contact with many patients, employees, and family members despite placing him in isolation. An investigation team should take which of the following steps to find out what went wrong?

A) Identify the index case, the first case identified in a particular outbreak.
B) Identify secondary cases, those patients who were diagnosed with active TB and who had contact with the index patient.
C) Identify all contacts.
D) All of the above