Sector A and Sector B each subtend an angle of 90∘ at the centre of their respective circles. The length of the arc of Sector A is 11 cm, while the area of Sector B is 154 cm2. Taking π=722, what is the ratio of the radii of their circles rA:rB?
a) 1:4
b) 1:2
c) 1:2
d) 2:1