Shelia's friends noticed that her behavior changed suddenly. She began to stay up late into the night, rarely sleeping. She impulsively decided to paint every room in her house and to buy all new furniture for her house. She also started drinking more and engaging in risky behavior, such as unprotected sex. Her friends noticed that when she spoke, she spoke very rapidly and quickly jumped from subject to subject. What may Shelia be experiencing?
A) schizophrenia
B) posttraumatic stress disorder
C) a depressive episode
D) a manic episode