Please answer the following question: Read the article and select the best answer. Article: Top student Lin Yijian had a problem recently . The 14-year-old boy from Xiamen used to get marks of over 110 points (out of 120 possible points)on his math tests . But during last semester's final exams , his math score was only 90 points . It was a shock . "I didn't know what happened , "said Lin , who kept feeling nervous and frustrated about math during the following month. . Like Lin , many of us have setbacks in life . What would you do to deal with these setbacks ? Would you just let them be and give up ? Lin chose to face his problem . His parents and teacher also gave him help . After some hard work he now gets marks between 100 and110 points on his math tests . Although he still isn't at his original level , Lin doesn't panic anymore . "Don't be scared by setbacks ,"he said . "You will beat it . " Chen Xingzhu in Shenzhen also has a story to tell . The 15-year-old girl is not good at doing sit-ups ,which is necessary for the coming high school PE entrance exam . One has to do at least 35 sit-ups in a minute to pass the test . Most of Chen's classmates can do 40 . However , Chen could only do 20 . Feeling worried , Chen decided to do something . She did sit-ups for half an hour every day after school . Now , after a month , she can do 30 sit-ups a minute . "I finally found what made me slow through continuous practice and then improved little by little , "said Chen . "I believe next month I will be able to do 40 !" Question: What problem did Lin YIjian have recently ? Options: A: He used to get high marks . B: He did well in math . C: He did not so well as bofore in math . D: He had no time to study math .
A:
C