State and explain the trend in electron
affinity shown by halogens

As fluorine sits atop chlorine in the periodic table, most people expect it to have the highest electron affinity, but this is not the case. ... Therefore, chlorine has a higher electron affinity than fluorine, and this orbital structure causes it to have the highest electron affinity of all of the elements.

B. nuclear reactions could first occur.

The answer is  d.  hydrogen