Read the excerpt from Mark Twain's essay "The Art of Inhumation." About the same time, I encountered a man in the street, whom I had not seen for six or seven years; and something like this talk followed. I said,-- "But you used to look sad and oldish; you don't now. Where did you got all this youth and bubbling cheerfulness? Give me the address." He chuckled blithely, took off his shining tile, pointed to a notched pink circlet of paper pasted into its crown, with something lettered on it, and went on chuckling while I read, "J. B-, UNDERTAKER." Then he clapped his hat on, gave it an irreverent tilt to leeward, and cried out,-- "That's what's the matter! It used to be rough times with me when you knew me--insurance-agency business, you know; mighty irregular. Big fire, all right--brisk trade for ten days while people scared; after that, dull policy-business till next fire. Town like this don't have fires often enough--a fellow strikes so many dull weeks in a row that he gets discouraged. But you bet you, this is the business! People don't wait for examples to die. No, sir, they drop off right along,--there ain't any dull spots in the undertaker line. I just started in with two or three little old coffins and a hired hearse, and now look at the thing! Based on this excerpt, which best describes this type of nonfiction?
a)humorous essay
b) essay of ideas
c)autobiography
d)biography