单项选择题

1998年到2002年,我国城镇登记失业率分别为()

A.2%,3.1%,4.5%,5.6%,7%
B.3%,3.1%,3.2%,3.3%,3.4%
C.3.1%,3.1%,3.1%,3.6%,4%
D.3%,3.5%,4%,4.5%,5%