In the context of corporate governance explain the role of the external company auditors, paying particular regard to the following issues:(a) their qualifications;(b) their powers;(c) their duties. (10 marks)

某机械厂电焊间门口电焊工吴某准备割一空桶的顶端进未进行检查，而且又没有开启端面上小盖，在空桶呈密闭状态下吴某点火操作，当顶部刚割穿一个小洞时，一声巨响，伴随着一股刺鼻的焦水味，桶盖飞出28米外，桶体向右上方弹出22米，吴某被气浪击倒，七孔流血，经抢救无效死亡，事故原因是（）。

A、未开启小孔盖

B、密闭容器不切割

C、违反焊工十不烧规定