For which purpose and audience would a poster be the most effective of document?

The correct answer would be option B "Encouraging the student body to come to the monthly poetry slam", because, a poster is usually an eye catching document, and its purpose is mainly to inform and convince, and is most commonly used with large audiences, so all of the above fits perfectly with trying to convince the student body of attending someplace.

its a hard situation i cant really answer because the essay is for you to write.

in ray bradbury's short story "a sound of thunder", mr. eckels's fearfulness leads to drastic consequences for the rest of the world.

in the story, mr. eckels, who is a hunter, hires a time travel company to travel to the age of dinosaurs. although he is excited for the hunting expedition at the beginning, when they reach there and mr. eckels sees the tyrannosaurus, he feels frightened. as he is afraid of the tyrannosaurus, he steps off the path although he has been warned not to do it. by stepping off the path, the entire course of the future is affected: mr. eckart alters the future by stepping on a butterfly, which causes a new man to be elected president in the future. in that way, it is mr. eckart's fearfulness what triggers 'the butterfly effect' and what leads to drastic consequences for the rest of the world.