Question:
The first clause (everything before the semi colon) definitely does not cause what is explained in the second clause (everything after the semi colon), so “therefore” is an inappropriate transition. This sentence is presenting contrasting professions (firefighter/police officer and doctor/lawyer) since two are viewed as blue-collar (working class) and the others are white-collar (professional); therefore, a contrasting conjunction is needed. Answer “therefore”, answer “as a result”. In this sentence “but” is not your best option for a conjunction. A semi-colon is used, so the three simple conjunctions (and/but/yet/etc.) are not as appropriate as the complex conjunctions (therefore/however/nevertheless/etc.). If just a comma was used, then “but” would have been appropriate (i.e. “...into the way of danger physically, but professionals such as doctors...”). So now it’s down to “nevertheless.”