【单选题】

The client is taking medication to control his cancer pain. Which of the following statements indicates that the client needs further instruction
A．"I should take my medication around-the-clock to control my pain. "

B．"I should skip doses periodically so I don't get hooked on my drugs. "
C．"It is okay to take my pain medication even if I am not having any pain. "
D．"I should contact the oncology nurse if my pain is not effectively controlled. "