Final answer:
The missing word in the sentence is a noun that officials must be aware of in order to take action; it could be 'concern,' 'issue,' 'complaint,' or 'request.'
Step-by-step explanation:
If officials do not know your concern, they cannot act on it. This sentence requires a noun to fill in the blank, which represents something officials are not aware of and thus are unable to address. The missing word would typically be a synonym for 'issue,' 'complaint,' 'request,' or a similar term depending on the context. Without knowledge of a concern, officials are powerless to respond to it or implement changes because they are unaware of the problem or suggestion.