诱发物

例句：

1. 1. The chemical was found to be a trigger for the allergic reaction.
   这种化学物质被发现是引发过敏反应的触发因素。
2. 2. The experiment was designed to test the effect of different stimuli on learning.
   这个实验旨在测试不同刺激对学习的影响。
3. 3. The researcher discovered that certain environmental factors could be triggers for mental health issues.
   研究者发现某些环境因素可能是心理健康问题的触发因素。