下面是按“四舍六入五凑偶”的舍入规则把各有效数字取为 4 位,正确是的( )
A. 21.495=21.50, 34.465=34.47, 6.1305×10 5 =6.131×10 5
B. 8.0130=8.013, 1.798501=1.798, 0.0028760=0.0029
C. 8.0130=8.013, 1.798501=1.799, 0.0028760=2.876×10-3
D. 21.495=21.49, 34.465=34.46, 6.1305×10^5=6.131×10 5