Read the following excerpt from a biography on Mark Twain and answer the question.
1Samuel Langhorn Clemens, Mark Twain, was born in Florida, Missouri on November 30,1835. 2The experience of his life prepared him as a writer, an American writer. 3He worked as a printer, then apprenticed himself as a river pilot on the Mississippi, and eventually became one of the best. 4He worked at mining activities in Nevada. 5In 1862, he took a position on the Virginia City Enterprise where he first used the name Mark Twain, which was a riverboat pilot expression.6He went to the West Coast and worked for a while on the San Francisco newspaper, Morning Call. 7After leaving there, he went to Calaveras County to try his hand at mining. 8In 1865, he was asked by Artemus Ward to write a humorous sketch. 9He signed it "Mark Twain," and his reputation began on the eastern seaboard. 10In 1866, he was sent by the Sacramento Union to Hawaii. 11Unexpectedly, in 1867, he sailed abroad and wrote letters that were to become the book, The Innocents Abroad. 12With that book he became the most famous humorist of his time. 13In July, 1869, The Innocents Abroad was published. 14On February 2,1870, he married Olivia Langdon.
What is the denotation of "sketch" in sentence 8?
A. a drawing
B. a piece of writing
C. a place to draw
D. an outline