Answer:
1. Nothing can be left in the past.
Step-by-step explanation:
Ray Bradbury's "A Sound of Thunder" is a science fiction story set in the year 2055. It revolves around the story of a man going back into the past to enjoy hunting dinosaurs but ended up disturbing the past.
In the story, the character Eckles had hired a travel agency, "Time Safari Inc." to take him back to the age of dinosaurs so that he can go on a hunting expedition. While there, they began shooting the dinosaurs but were asked to retrieve the bullets as they cannot leave anything behind. The tour guide, Travis explains, "The bullets! The bullets can't be left behind. They don't belong in the Past; they might change anything."
Thus, the correct answer is option 1.