Determine whether the underlined portion of the sentence below is correct or whether it needs to be revised.
Firefighters and police officers risk their lives often by stepping into the way of danger physically; therefore, professionals such as doctors and lawyers have an equally significant impact on individuals’ lives medically and legally.

The first clause (everything before the semicolon) definitely does not cause what is explained in the second clause (everything after the semicolon), 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 semicolon 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.”