Step 1: Use context — a smell noted as 'peculiar' in a lab setting is one that stands out as unusual or odd. Step 2: Analyse the target word — 'peculiar' means strange, odd, or unusual in a way that stands out. Step 3: Match to the synonym — 'strange' best captures the unusual quality of peculiar. The other three options (familiar, common, ordinary) all describe things that are normal or unsurprising, which are antonyms of peculiar.