Which of these authors did not write mainly for enterainment?

A Upton Sinclair
B Stephen Crane
C Charlotte Perkins Gilman

To determine which of these authors did not write mainly for entertainment, we can look into the works and writing styles of each author.

A) Upton Sinclair: Upton Sinclair was an American writer and political activist who is best known for his novel "The Jungle," published in 1906. "The Jungle" exposed the harsh conditions and exploitation of the American meatpacking industry, shedding light on social and economic issues rather than focusing on entertainment.

B) Stephen Crane: Stephen Crane was an American novelist, poet, and short story writer. He is best known for his novel "The Red Badge of Courage," published in 1895. The novel is a classic work of American literature that explores the psychological complexity of war. While it can be considered a work of literature, it is also known for its realistic depiction of battle rather than being primarily intended for entertainment.

C) Charlotte Perkins Gilman: Charlotte Perkins Gilman was an American writer, lecturer, and feminist social reformer. Her most famous work is the short story "The Yellow Wallpaper," published in 1892. This story tackles the issue of women's oppression and mental health in a patriarchal society, focusing on social commentary rather than pure entertainment.

Based on this information, it can be concluded that all three authors—Upton Sinclair, Stephen Crane, and Charlotte Perkins Gilman—did not primarily write for entertainment purposes.