Put your reasoning to work.

A. Hypoxaemia, tachypnoea and hypotension make outpatient management unsafe.

B. Pulse oximetry and clinical distress already justify oxygen while further assessment proceeds.

C. The focal air-space opacity and infectious syndrome support pneumonia; anticoagulation is not justified by the image.

D. Imaging repetition should not delay time-critical treatment in possible sepsis.

A. Tends to cause intraparenchymal or subarachnoid bleeding, not a trauma-related biconvex collection with a lucid interval.

B. These cause subdural haematomas, which are crescentic and cross suture lines, typically in elderly/anticoagulated patients.

C. Cause hypertensive intraparenchymal bleeds in the basal ganglia, not extra-axial collections.

E. Causes subarachnoid haemorrhage with blood in cisterns/sulci, not a biconvex extra-axial collection.

A. Urticarial weals are transient (each lasting <24 h), migratory and lack a fixed dusky/blistered centre; fixed concentric three-zone targets are not urticaria.

B. Bullous pemphigoid affects older patients with tense bullae on urticarial plaques over flexures/trunk, not young adults with acral targets; the morphology, demographic and post-herpetic timing do not fit, and systemic steroids are not first-line for self-limiting EM minor.

C. Gonococcaemia produces sparse pustular/haemorrhagic acral lesions with fever and arthralgia in a systemically unwell patient, not symmetrical concentric targets after herpes labialis; she is afebrile and well.

D. This is the trap: SJS shows atypical FLAT targets plus purpuric macules, near-universal mucosal ulceration (92-100%), painful detaching skin with a positive Nikolsky sign, and a drug trigger in a systemically unwell patient. The well-formed RAISED acral three-zone targets, absent mucosal involvement, minimal detachment and a viral trigger in a well, afebrile patient defeat the SJS diagnosis.

B. A positive DAT indicates immune haemolysis, which produces a normocytic or macrocytic picture with spherocytes, not the microcytic hypochromic film driven by dietary iron deficiency.

C. Iron deficiency impairs erythropoiesis, so the reticulocyte response is inappropriately low rather than raised; a brisk reticulocytosis would suggest haemolysis or blood loss with intact iron stores.

D. A raised HbA2 indicates beta-thalassaemia trait; while it also causes microcytosis, the dietary history points to iron deficiency, in which HbA2 is normal or even low.

E. Lead poisoning can cause microcytic anaemia with basophilic stippling, but it is uncommon in this setting and the dietary story makes simple iron deficiency far more likely; ferritin is the targeted next test.

A. In 2:1 block alternate P waves conduct with a fixed PR, giving exactly two P waves per conducted QRS; this trace shows P waves that bear no fixed relationship to the QRS at all (variable PR).

C. Wenckebach shows progressive PR lengthening then a single dropped QRS, and conducted beats retain a fixed P-QRS relationship, unlike the total AV dissociation seen here.

D. First-degree block keeps every P wave conducting with a constant prolonged PR; there is no AV dissociation, and each QRS is preceded by its own P at a fixed interval.

E. AF has no organised P waves and an irregularly irregular ventricular response; here discrete regular P waves and a regular ventricular rate are present.