Answer:
C 90-degrees
Explanation:
Using alternate interior angles, you can say m<CGD = 50 degrees.
From here, using the fact that line BE is a bisector of line CF, we know that the sum of degrees of the line BE would be 180 degrees.
So we can say m<EGD + m<CGD + m<BGC = 180. Plug in our known values.
90 + 50 + m<BGC = 180
m<BGC = 40
And we can see that m<BGD = m<BGC + m<CGD
Thus, m<BGD = 40 + 50 = 90.
So the m<BGD = 90 degrees.
Cheers.