Answer:
Option B is correct.
the measure of angle HGI is 21°
Step-by-step explanation:
By Angle bisector definition:
A line that bisects the angle into equal angle
From the given figure, we have;
and 
it is given that: GH bisects ∠FGI.
then by definition:

Substitute the given values we have;

Add 9 to both sides we get;

Subtract 2x from both sides we get;

or

then;

Therefore, the measure of angle HGI is 21°