Answer:
3 / 4
Explanations:
The given fractions are 6/12 , 9/18, 3/4, and 4/8
For 6/12
For 9/18
For 3/4
3/4 is already the simplest term, It cannot be reduced further
For 4/8
6/12, 9/18 and 4/8 reduced to 1/2 except 3/4
Therefore, 3/4 does not belong to the group