what should you always avoid in formal writing?\na. dates and signatures\nb. complete sentences\nc. slang or…

Brief Explanations:

Formal writing requires a professional tone. Slang and filler words are too casual and undermine the formality. Dates and signatures are often needed in formal documents like contracts or letters. Complete sentences are essential for clarity. A personal voice can be appropriate in some formal - like opinion - pieces but slang and filler words are always inappropriate.

Answer:

C. Slang or filler words