A - Although he denies them, Dr. Vasequez faced several scandals last year.
A complex sentences must have both a dependent clasuse (although he denies them) and an independent clause (Dr. Vasquez faced several scandals last year.
Options B and D are compound sentences (two independent clauses) and option C is a simple sentence.
This question is rather old but I always make up a new answer when I scroll by it >w<
Animals can in fact understand us humans and other animals. They show this by reactin to us with body movements and sounds. I don’t believe that they understand our language, but they understand our tone of voice and behavior. Aka, why we are able to train animals :)
