The effect of setting a boring tool above center height leads to

When a boring tool is set above the center height, it changes the angles at which the tool interacts with the workpiece.
Imagine the tool is slightly "tilted up".
Rake Angle:
The rake angle is the angle at which the cutting face of the tool meets the workpiece.
If the tool is tilted upwards (above center), the effective rake angle decreases.
Think of it as the tool becoming less "sharp" for cutting.
Clearance Angle:
The clearance angle is the angle between the flank of the tool and the finished surface of the workpiece.
This angle prevents the flank from rubbing against the workpiece.
If the tool is tilted upwards, the effective clearance angle increases.
This provides more space to avoid rubbing.
Conclusion:
Therefore, setting a boring tool above center height leads to a decrease in the effective rake angle and an increase in the effective clearance angle.
So, the correct answer is Option C.