Sentence:  Risk behavior in driving consists in <WSD>hazard</WSD> detection, threat appraisal, action selection and implementation. <WSD>Hazard</WSD> perception tests often include the task to react quickly to <WSD>hazards</WSD> within traffic scenarios. 
Meaning of the word marked with <WSD> tags:  An obstacle or other feature that presents a risk or danger that justifies the driver in taking action to avoid it.