Why,according to Research by William McGuire (1964),does Attitude Inoculation Work

Why,according to research by William McGuire (1964) ,does attitude inoculation work to increase resistance to subsequent persuasion attempts? Attitude inoculation

A) generates psychological reactance,so people ignore subsequent messages.
B) encourages people to think about the issues and to generate counterarguments.
C) raises self-esteem,and thus makes people less vulnerable to later persuasion attempts.
D) increases fear,and thus make people less responsive to logical arguments.