38. Which of the following suggestion is not advisable for the use of opioids in children with cancre pain? (A) Use the oral route first in most circumstances (B) Treat constipation pre-emptively. (C) If side effects are bothersome with one opioid, consider switching to another one. (D) Use sufficient doses to keep the patient comfortable should be avoided due to the possible occurrence of adverse effects (E) Use the oral route first in most circumstances.