This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Intravenous Anesthetic Agents, Subject name: Anaesthesia
Which of the following is true about the WHO analgesic ladder for chronic pain in adults? 
Select and explain. 
A. Analgesics are given 'on demand', B. Morphine used for severe pain, C. Adjuvants are indicated only for mild pain, D. Non opioid analgesic are given for moderate pain.
B: Morphine used for severe pain
Answer: B: Morphine used for severe pain 
Explanation: The 3 main principles: By the clock: Drugs should be given "around the clock" rather than "on demand". By the mouth: Oral route is preferred. By the ladder: Non-opioids - Mild opioids - Strong opioids. Non opioid analgesic are given for mild pain. Adjuvants can be used for mild, moderate and severe pain