Rudolf has been reading names at commencement exercises every year for the past twenty years. An average of 700 students have been going to graduation each semester, handing him their name card with their first, middle, and last name, and waiting eagerly for him to read it over the PA system. Rudolf usually flubs only three names, either the first, middle, or last during the entire ceremony. What is his sigma level? a. 4.48 b. 3.40 c. 4.13 d. 4.72