Final answer:
Among the options provided, metabolic acidosis is the condition most likely to cause an increased anion gap, as it involves an accumulation of unmeasured acids in the blood.
Step-by-step explanation:
An increased anion gap generally indicates the presence of acids in the blood that are not being measured as part of the usual panel of laboratory tests. Among the provided options, b) Metabolic acidosis is the condition most likely to cause an increased anion gap. Metabolic acidosis results from a surplus of acid in the body, which can occur for various reasons, including ingestion of acidifying substances or decreased acid excretion due to kidney dysfunction.
Diarrhea can cause a loss of bicarbonate and potentially lead to a non-anion gap metabolic acidosis, without necessarily increasing the anion gap. Hyperventilation and respiratory alkalosis involve changes in carbon dioxide levels and do not directly affect the anion gap.