Answer:
Hi! Unfortunately, I can't give you the precise answer because your question is incomplete. I guess you should have options for the word missing, so I'll try to help you anyways, so that you can do this task by yourself.
Step-by-step explanation:
As I said before, you probably have options for completing the sentence. You should carefully read the sentence again and carefully study the options. You will realize that there is one that makes total sense, according to the context and the whole idea of the text. If you feel that there is more than one option that would suit the sentence, just think of the whole text as a single idea and choose the one that you see completes the idea and spirit of the text. Don't worry you'll do fine, you just have to pay attention and choose the one word that best fits the sentence and its spirit. Remember it has to be only one word, since you have only one line and that gives you the idea that what is missing is just one word.
Hope this helps! Good luck!