Final answer:
Option c, 'a decrease in goal-directed activity,' is NOT a characteristic of mania. Mania typically involves increased, not decreased, goal-directed activities.
Step-by-step explanation:
The question asks which option is NOT a characteristic of mania. Mania is a state typically associated with bipolar disorder that includes symptoms such as heightened energy, reduced need for sleep, and overconfidence.
Answer choices a, b, and d (an excessive involvement in risky activities, a decreased need for sleep, inflated self-esteem or grandiosity) are all characteristics of mania. Therefore, the correct answer is c, a decrease in goal-directed activity, as mania tends to increase goal-directed activities, contrary to what is suggested in this option.