How does the structure of the section “The Investigation” support the purpose of the passage?
A. Its sequence structure explains how epidemiologists solved Centerville’s problem.
B.Its cause-and-effect structure explains why the epidemiologists were able to help Centerville.
C.Its compare-and-contrast structure explains how epidemiologists are different from other scientists.
D.Its problem-and-solution structure explains the difficulties epidemiologists encounter in their work.