Complete the sentence with the appropriate word. Pedestrians should be…

In a sentence-completion (fill-in-the-blank) question testing vocabulary in context, the blank must be filled with the word whose meaning logically matches the situation set up by the rest of the sentence — in particular, a reason clause (introduced by 'as' or 'because') that explains WHY a certain quality or behaviour is required.

Here, the reason clause 'as the roads get slippery' explains why a particular quality is expected of pedestrians walking in the rain: slippery roads increase the risk of falling or being involved in an accident, so pedestrians need to be careful and alert to that danger. The word 'cautious' means exactly this — careful, watchful, and mindful of possible danger — so it is the word that logically completes the sentence.

• 'dangerous' describes a risky or hazardous quality that a thing or situation (such as the roads themselves) can have; it does not describe how a person behaves, so it cannot logically complete 'Pedestrians should be __________' as a description of safe conduct.

• 'clever' means mentally sharp or quick-witted, a quality about intelligence that has no bearing on the physical care needed to avoid slipping on wet roads.

• 'smart' likewise refers to intelligence or sharpness of mind, not to watchfulness or care in the face of a physical hazard, so it does not fit the safety context set up by the reason clause.

Reading the completed sentence back — 'Pedestrians should be cautious when walking on the roads on rainy days, as the roads get slippery' — the reason clause and the chosen word line up logically: slippery roads are the hazard, and being cautious is the appropriate protective response, confirming the fit.