B. The types of chemical elements can be distinguished according to the radicals of Chinese characters, and the names of metal elements generally have the word "gold" next to them; Iridium is a metal element, so B is wrong;
C. According to the data, the relative atomic mass of iridium is 192, so c is wrong;
The relative atomic mass of d iridium is 192, so d is wrong;
So choose a.