The correct answer is B. audacity.
Audacity is the quality of being bold and daring, especially in a way that is disrespectful or challenging. In the sentence “He had the nerve to suggest that I was cheating,” the man is being accused of having the audacity to make such a suggestion. This suggests that the man is being bold and daring, but also that he is being disrespectful and challenging.
The other options are not as accurate. Courage is the ability to do something that is difficult or dangerous, despite fear. Capacity is the ability to hold or contain something. Strength is the quality of being physically or mentally strong. None of these options accurately describe the man’s behavior in the sentence.