Well if you're during the editing stage of your letter, the only option that would make sense would be C. Verify that all facts and numbers in your letter are accurate.
Hey there
___________
The correct answer is:
Nitrogen is a key element in the formation of B. amino acids ,which are substances necessary to living organisms.
_______________
Hope this helps you
The correct answer should be <span>by invoking their muse
The muse is a source of inspiration. If you look at Iliad, he starts by saying "Sing, O, Goddess", where he mentions the muse as a goddess because she is the one who enabled him to tell the story with her inspiration. This is quite common in ancient Greek Epics. The Greek gods are however mentioned later and are often the central part of all epics, aside from heroes since usually the course of things is that they made a mess between each other and the people are the ones who have to suffer the consequences.</span>