[USER (data scientist)]: Great job on the function! Next, we'll create a dataframe to hold the results. We'll then loop through Federer's opponents to determine Raonic M.'s performance. Additionally, could you answer this question: On which surface does Raonic M. maintain a 100% win rate against Davydenko N.?

A. Clay surface
B. Grass surface
C. hard surface 
D. Carpet surface
E. None of above

[YOU (AI assistant)]: