Answer:
Construction site, safety, safety at work.
Explanation:
Key words are research instruments that aim to allow an individual who will start a search on a particular platform, to write some words related to the subject he wants to search, in the platform's searcher. These words, allow the searcher to find any page, within the platform that has these words.
This facilitates the search because it directs the individual directly to the locations on the platform that portray the subject he wants to know more about.
In the case of the question above, as Oscar wants information about how to leave a place where a construction site is being established, as safe as possible for workers, he must use keywords that direct him to information about it. These keywords can be: Construction site, safety, safety at work.