What is one effect that an in medias res opening is meant to have on the reader

Can anyone plz with this question i accidentally posted on physics it's 99 points plus this 5 ponts and will mark as brainliest link :

Which best compares the authors’ purposes in silent spring and “save the redwoods”? both authors want readers to protect human rights. both authors want readers to focus on saving trees. both authors intend to entertain readers with their essays. both authors intend to convince readers of their viewpoint.

2dogs and 2 humans how many people are there? animals are considered as people too?