The base radii of two cylinders are in the ratio 4 : 5 and their heights are in the ratio 2 : 9. The ratio of their curved surface areas is:

8 : 45

Curved surface area of cylinder = 2πrh

                      CSA1     :      CSA2

                      2πrh      :      2πRH

                         rh       :         RH 

                     4 × 2      :        5 × 9

                        8          :          45

The correct answer is Option (1) → 8 : 45