Answer:
Option B [tex]90\°[/tex]
Step-by-step explanation:
we know that
The inscribed angle is half that of the arc it comprises.
In this problem the inscribed angle is the measure of angle B
so
[tex]m<B=\frac{1}{2}arc\ AD[/tex]
we have that
[tex]arc\ AD=180\°[/tex] -----> the diameter divide the circle into two equal parts
substitute
[tex]m<B=\frac{1}{2}180\°=90\°[/tex]
