Final answer:
Cognitive dissonance is most likely to occur during the Postpurchase behavior stage of the purchase decision process, resulting from the psychological discomfort of inconsistent beliefs and behaviors, which disrupts the individual's need for consistency.
Step-by-step explanation:
Cognitive dissonance often arises when individuals engage in an action that contradicts their beliefs or attitudes, leading to psychological discomfort. This concept is particularly relevant in the purchase decision process. The most likely stage at which cognitive dissonance would occur is option (a) Postpurchase behavior. This is because after a purchase has been made, individuals might feel discomfort from any incongruence between their behaviors and prior beliefs. For instance, if someone buys a car but then realizes it consumes more fuel than they believe in for environmental reasons, the result could be cognitive dissonance. This discomfort can be resolved either by changing the behavior (for instance, selling the car) or by changing the conflicting belief (perhaps by downplaying the environmental impact).
Cognitive dissonance causes discomfort because it disrupts our sense of consistency. In the example provided, this might include an individual acknowledging the conflict between their environmental values and their new car's high fuel consumption. To ease the dissonance, one could either choose to prioritize the car's benefits over their environmental concerns, or they could take steps to mitigate the car's environmental impact.