A .
8/9 - 11/12 =
8×4/9×4 - 11×3/12×3 =
32/36 - 33/36 =
- 1/36
______________________________
B .
6/7 - 1/9 =
6×9/7×9 - 1×7/9×7 =
54/63 - 7/63 =
47/63
_____________________________
C .
15/16 - 3/8 =
15/16 - 3×2/8×2 =
15/16 - 6/16 =
9/16
____________________________
D .
3/5 - 6/11 =
3×11/5×11 - 6×5/11×5 =
33/55 - 30/55 =
3/55
_____________________________
1/2 = 0.5000
A . - 1/36 = - 0.0277
B . 47/63 = 0.7460
C . 9/16 = 0.5625
D . 3/55 = 0.0545
As you can see the closest difference to 1/2 belong to option C .
