I came across writing in history, and I hesitate on this situation. Is it "Christopher Columbus' expedition" or "Christopher Columbus's expedition"? Or is it something else?

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serve the people! ,” smoothly translated by julia lovell, offers an initial sample of yan lianke’s writing to an english-speaking audience. a bluntly drawn, mildly erotic fable, it teases mao zedong by poking fun at a true believer who obeys the chairman’s precepts too literally. to a western sensibility, the broad strokes of yan lianke’s humor would seem to pose little risk of inciting rebellion, whether of the flesh or of the body politic. but then, part of the book’s attraction is that it doesn’t have a western sensibility. it lets the reader see — or rather, intuit — what jokes chinese officials don’t consider funny, and how very little it takes for a writer to be branded an incendiary in 21st-century china, more than three decades after the death of mao, a decade after the death of deng xiaoping and seven years since china entered the world trade organization, a move that would seem to signal a willingness (however wary) to mingle with the rest of the world.

the answer is d because all the other ones are uplifting aging is sad