Study the given pie-chart and answer the question that follows. The pie-chart shows the data for A, B, O , AB blood groups of 240 donors.

The ratio of the donors of blood group 'O' to the average of the donors of groups 'A' and 'AB' is:

1 : 1

Ratio of donors of blood group 'O'  :   Average of the donors of groups 'A' and 'AB'

                     80º                         :       \(\frac{90º +20º }{2}\)

                     160º                       :             160º  

                       1                          :                1