Would you mind reading my research paper?" Ouisa asked her best friend Petrie. He smiled but shook his head. "I can't right now," he told her regretfully. "I have to finish this lab worksheet for biology before next period. If you can wait for half an hour, I can read it then."
"I hate waiting," said Ouisa. "Maybe someone else in the library will help me."
"It looks like Nagata is sitting in the corner over there," Petrie told her.
"Nagata and I are mortal enemies, Petrie," Ouisa reminded him. "We have been in competition with each other since we were in diapers. I can't ask her for a favor."
"It doesn't look like you have much choice," Petrie replied distractedly. He wanted to help his friend, but the pressure of having a report due after lunch was weighing on his mind. Ouisa tried not to let her hurt feelings show as she walked over to Nagata's table.
"I don't suppose you'd be willing to review my research paper?" Ouisa asked reluctantly. Nagata looked up at her in surprise.
"Of course, Ouisa!" she replied. "I'm always willing to help my classmates with their studies." As Nagata scanned the research paper, she grabbed her red marker and began making changes. Ouisa watched in horror as Nagata changed nearly every sentence.
"There you go," Nagata said when she was finished. "If you make these changes, you're guaranteed to get an A. I took Dr. Mikram's class last year, and I know exactly how he grades papers." Ouisa hurried back to Petrie with her mouth open in shock and tears welling up in her eyes.
"I never realized what a terrible writer I am," she told her friend. "I should start over from scratch." Petrie, who had finally finished his report, looked up at her in alarm. He took the paper out of her hands and began reading.
"Ouisa, this is ridiculous," Petrie said. "These changes don't make any sense. I think Nagata is trying to sabotage your grade."
"I should have known better than to ask her for help!" exclaimed Ouisa. "Next time, I will be patient and wait for help from a true friend."
"And I'll start finishing my homework

One of the themes of this passage is "waiting until the last minute to finish something can cause problems." How does the character of Petrie demonstrate this theme?
A.
He ignores Ouisa completely and loses her friendship.
B.
He postpones reading Ouisa's paper and causes her pain.
C.
He steals Nagata's ideas and uses them for his worksheet.
D.
He chooses not to finish his homework but to help Ouisa instead.