Any way to improve english vocabulary?

For english i have to find 4 errors in each diary post

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.

What did mark twain contribute to the history of the novel? select all that apply.