Answer:
The most important function of safety signs is to remind employees at critical/important junctures to be careful and remain aware. Safety signs can be installed pretty much anywhere and can contain any message that your business requires in order to keep your employees as safe as possible within the workplace
Explanation:
Compound. The simple sentence would be 'they were very busy'
The last one, Before his European travel- the highlight of his summer-... ect.
is the right answer