问题

About _________ of the engineers in my company seem to be in their _________.
A:second-nines; forties
B:two-ninths; forties
C:second-ninths; fortieth
D:two-ninths; fortieth;
B:two-ninths; forties
C:second-ninths; fortieth
D:two-ninths; fortieth;
正确答案是: