Answer the question on the basis of the information given below:
In the adjoining figure, I and II are circles with centres P and Q respectively. The two circles touch each other and have a common tangent that touches them at points R and S respectively. This common tangent meets the line P and Q at O. The diameters of I and II are in the ration $4:3.$ It is also known that the length of PO is $28$ cm.
What is the radius of the circle II?
- 2 cm
- 3 cm
- 4 cm
- 5 cm