Answer: C
Reason/Explanation:
A compound sentence is basically 2 sentences, if you were to take away the so, but, and , or, etc. C says processed foods should be avoided because they can lead to serious health problems. If you were to remove the "because" from the sentence, then that would become two sentences. That's what makes it a compound.
-I hope that helps, I apologize if I was wrong,
~DustinBR