This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Surgery
Which of the following can cause secondary brain injury 
Select and explain. 
A. Hypoxia, B. Intracranial pressure > 30mm Hg, C. Hypotension, D. All of the above
D: All of the above
Answer: D: All of the above 
Explanation: Causes of secondary brain injury
- Hypoxia: PO2 < 8 kPa
- Hypotension: systolic blood pressure (SBP) < 90 mmHg
- Raised intracranial pressure (ICP): ICP > 20 mmHg
- Low cerebral perfusion pressure (CPP): CPP < 65 mmHg
- Pyrexia
- Seizures
- Metabolic disturbance