Reading — Sentence completion

The missing word is "assumptions".. The passage states that critical thinkers must identify the hidden "assumptions" on which an argument rests, so assumptions is the accepted answer.

The light-emitting molecule that reacts with oxygen is called luciferin.. The passage names "luciferin" as the light-emitting molecule that reacts with oxygen to release energy, so luciferin is the accepted answer.

The passage specifically mentions luciferin as the molecule responsible for reacting with oxygen to produce light. A diagram for this topic isn't available yet — the worked example below walks the same reasoning step by step.

• !Some readers may confuse luciferin with other terms related to bioluminescence, but the passage clearly states its role. Others might overlook the specific mention of luciferin in the text.
• !Test‑takers sometimes guess synonyms like “public libraries” or “reading rooms,” but the answer must match the exact wording in the passage.
• !Some students might confuse the answer with another European city, but the passage clearly mentions Venice as the primary entry point.
• !Test‑takers sometimes guess words like "premises" or "biases," but the passage specifically uses the term "assumptions."

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