As shown in the figure, the straight line a and the straight line b are intercepted by the straight line c, b perpendicular  c, the foot of perpendicular is the point A, angle 1 = 70.0. If the line b is parallel to the line a, the line b can be rotated () clockwise around the point A 
Choices:
A:70°
B:50°
C:30°
D:20°
Please directly answer the question and provide the correct option letter, e.g., A, B, C, D.
Question: As shown in the figure, the straight line a and the straight line b are intercepted by the straight line c, b perpendicular  c, the foot of perpendicular is the point A, angle 1 = 70.0. If the line b is parallel to the line a, the line b can be rotated () clockwise around the point A 
Choices:
A:70°
B:50°
C:30°
D:20°
Please first conduct reasoning, and then answer the question and provide the correct option letter, e.g., A, B, C, D, at the end.
Question: As shown in the figure, the straight line a and the straight line b are intercepted by the straight line c, b perpendicular  c, the foot of perpendicular is the point A, angle 1 = 70.0. If the line b is parallel to the line a, the line b can be rotated () clockwise around the point A 
Choices:
A:70°
B:50°
C:30°
D:20°