Answer: Did the girl pass deadly bird flu directly to her mother?
Identifying the central idea of a text is an important step in analyzing and engaging with a text. This is because most items in a text are likely to link with the main idea. A good way to identify what the main idea of a text is is to present it as question and answer. In this case, presenting the central idea in the form of a question would look something like option B. The rest of the document attempts to reach an answer for this central question.