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there are several reasons why travelers often become ill. first of all, unfamiliar foods and water in foreign countries can cause digestive upsets. in addition, fatigue—the result of jet lag and the strain and exertion of traveling—lowers the resistance of travelers. travelers may also become ill because of exposure to diseases to which their bodies never developed any natural immunity.

the selection’s main pattern of organization is: (click on the pattern of organization.)

a. definition and example.

b. comparison.

c. contrast.

d. cause and effect.