Step 1: Use context clues — Jun Jie is completing Science experiments carefully, which suggests precision and attention to detail. Step 2: Analyse the target word — 'meticulous' means showing great attention to detail and being very thorough and precise. Step 3: Match to the synonym — 'careful' best captures the idea of being thorough and precise. The other options (careless, quick, lazy) carry opposite or unrelated meanings.