Respuesta :
Answer: A textbook written last year by a professor of engineering.
Explanation: For a source to be credible, it has to have a current copyright date, and last year is mostly accurate. It should also be an expert or a professional of some kind, so a professor of engineering is very credible.
Hope this helps!
Answer:
the answer is C. a textbook written last year by a professor of engineering
Explanation: