4.21 Point Grading comment: Suppose I want to sum up a integer list. Which of the following functions should I use when calling reduce? Choice 1 of 6:lambda x,h: x + h Choice 2 of 6:lambda x,h: h Choice 3 of 6:lambda x: x Choice 4 of 6:lambda x,h: x Choice 5 of 6:None of the above Choice 6 of 6:Multiple of the above