问题

mber of the workers in this factory 300, that is to say,it 20%.
A:has increased by; has increased to
B:have increased to; have increased by
C:has increased to; has increased by
D:have increased by; have increased to;
B:have increased to; have increased by
C:has increased to; has increased by
D:have increased by; have increased to;
正确答案是: