C for me as well.
From 1, you only know the radius/diameter of the circle, which only gives you one side of the rectangle. insuff.
From 2, the sides could take on many different values, since all we know is a ratio. insuff.
Together, from 1 we can find the radius and diameter, which gives us the length of the rectangle, and then using the ratio, we can find the width. Sufficient.
I don't think that knowing the radius/diameter of the circle gives one side of the rectangle.
Else: what would be this side for a circle of diameter 10cm ?