B

Repeated vomiting causes loss of hydrochloric acid and potassium, producing a hypochloraemic, hypokalaemic metabolic alkalosis that is best corrected by restoring extracellular volume with isotonic (0.9 %) saline and replacing potassium chloride intravenously. This combination supplies both chloride to allow renal bicarbonate excretion and potassium to correct the accompanying hypokalaemia, reversing the alkalosis [Gillion et al., 2019, PMID 30369299; Heymer et al., 2018, PMID 30662230].