请选择DCBA5a7Y5I5c9d2P6W*M-T7\ Computers are so popular in our country that every pupil knows___________e-mails.:O0q9F.r
A. how can he send:O0q9F.r
B. how does he send:O0q9F.r
C. how to send:O0q9F.r
D. how sending:O0q9F.r