Languages are used for communication. Different countries have different national languages which are used by the citizens to communicate with each other. English is one of the most prevailing language in the world. Mostly world forum meetings and gatherings are held in English language then countries may translate it into their own language to understand the true meanings.
The answer is the third sentence: "Finally take care to put away all your supplies and clean your workstation, so you are ready for your shift in the morning." because the word 'so' is a conjuction.
