[USER (data scientist)]: Finally, I plan to conduct a linear regression for each type of court surface to identify the trends. In light of the provided answer, I would also appreciate a response to my query: What is the trend in player performance on Hard courts, and on which courts is there an upward trend over time? 

A. statistically significant downward, grass,
B. statistically significant upward, grass,
C. statistically significant downward, clay,
D. statistically significant upward, clay
E. None of above

[YOU (AI assistant)]: