The correct answer is A. overwhelmed.
The word “inspired” means to be filled with enthusiasm or motivation. When someone is overwhelmed, they are feeling too much pressure or stress. This can be caused by a number of things, such as a difficult task, a stressful situation, or a lot of responsibility. When someone is dispirited, they are feeling discouraged or disheartened. This can be caused by a number of things, such as failure, disappointment, or loss. When someone is disillusioned, they have lost their belief in something or someone. This can be caused by a number of things, such as betrayal, disappointment, or a change in circumstances. When someone is skeptical, they are doubtful or questioning. This can be caused by a number of things, such as a lack of evidence, a lack of trust, or a difference in opinion.
In the given sentence, the man returned home much inspired. This means that he was filled with enthusiasm or motivation. This is likely because the plan had worked, which would have given him a sense of accomplishment and satisfaction. It is unlikely that he was overwhelmed, dispirited, disillusioned, or skeptical, as these emotions are not typically associated with success.