When using if and can't they both have the similar "self doubt" aspect in them. Like "If I can do it..." and "I can"t do it." Both of these statements are basically questioning their self worth.
The root words meaning two are:
bi-
di-
The text does not provide any definitions, thus, options a. definition-example and cause-effect and c. comparison-contrast and definition-example can be out ruled...There are provided examples just not definitions. The text does show patterns of cause and effect--such can be shown with sentence (6) "Clearly the feeling of being anonymous causes people to engage in antisocial behavior." This sentence shows that the cause (anonymity) can lead to the effect (antisocial behavior). Hence, the correct option is b. cause-effect and comparison-contrast.