Concept:The mode is the value that appears most frequently in a data set.Explanation:List the given scores: 4,3,3,2,1,2,5,7,8,3,5.Count how many times each mark occurs.1 appears once, 2 appears twice, 3 appears three times, 4 appears once, 5 appears twice, 7 appears once, and 8 appears once.The highest frequency is 3, which belongs to the mark 3.Therefore, the mode of the marks is 3.Answer:3 (Option B)