The root most likely to be pushed into sinus during extraction is.. Palatal root of maxillary 1st molar

The root most likely to be pushed into sinus during extraction is?
A. Palatal root of maxillary 2nd molar
B. Palatal root of maxillary premolar
C. Palatal root of maxillary 1st molar***
D. mesio-buccal root of maxillary 1s molar.