In the following question, out of the four alternatives, select the alternative which will improve the bracketed part of the sentence. In case no improvement is needed, select "no improvement".
They are giving something back to the planet that (being defiled) every day in a thousand ways.
Two circles of same radius intersect each other at P and Q. If the length of the common chord is 30 cm and distance between the centres of the two circlesis 40 cm, then what is the radius (in cm) of the circles?