Question 12 is based on the passage you have just heard.

12. What does the speaker warn about at the end of the talk?

解析：C。本题目为细节题。问题为：讲话人在讲话最后提出了什么警告？原文所在句：People who live, hunt, or fish near bird colonies need to be careful, the researchers say. The birds don’t mean to cause harm, but the chemicals they carry can cause major problems. 研究者说，在鸟类栖息地附近生活、捕猎和捕鱼的人需要特别注意，虽然海鸟不是故意造成伤害，但它们所携带的化学物质会引发大问题。选项C) The harm Arctic seabirds may cause to humans（北极圈海鸟可能给人类带来伤害），与文中这一信息完全一致。选项B、D可直接排除，均属于无中生有。选项A属于因果倒置，A说人类对海鸟造成了威胁，实际上讲话最后想表达是海鸟携带的化学物质对人类有伤害。