A 65-year-old woman with COPD and long smoking history presents with worsening somnolence and headache. ABG on 2 L/min oxygen shows pH 7.25, PaCO₂ 70 mmHg, PaO₂ 55 mmHg. What is the most appropriate immediate management?AIncrease oxygen to 15 L/min via non-rebreather mask onlyBReduce oxygen to target SpO₂ 88-92% and start non-invasive ventilationCStop oxygen and observeDIntubate immediately without trial of non-invasive supportEGive morphine for headache and dyspnoea and observeCheck my answer