Which sentence from a research paper on currently popular fitness trends (like crossfit) demonstrates how to directly quote a source (rather than how to paraphrase a source)?

a) the number of summer fitness boot camps and crossfit openings have skyrocketed in major cities since 2010.

b) crossfire owner, chris brannon claims that "our enrollment has increased by 60% in the last six months alone."

c) similar to how fad diets occasionally sweep the nation, new fitness trends have arisen and become almost omnipresent on social media.

d) while popular, not all fitness experts are with the sudden rise of extreme fitness trends that are not appropriate for everyone.

in the secret life of walter mitty, the main character leads a dull life, or so he thinks.in all his daydreams he plays the role of some hero or a man who is unbelievably resourceful.whether a pilot, a surgeon   or even a criminal, he is better, so much better than all the rest of the characters in his delusions.he comes up with ideas nobody else could have conceived .when he comes back to reality, whatever he has to deal with seems silly, boring without any motivation to deliver.

in a sound of thunder a hunter,eckles, wants to use a time machine to go back in time to catch a tyrannosaurus rex. by then, 2055 elections were go held and a   new hitler was beaten by a far better candidate, keith.once he and other men have traveled,   he gets cold feet. he in   some way has known   this is not a good idea.he hears this sound , too strong for him to put up with . hopeless, he abandons the project making a mistake - another one as the first is to travel in time-that causes a butterfly effect when he comes back. in the end , changes reality for worse; the anti human anti christ deutscher,   is the president.