Answer :

First we make the fractions homonym ( they must have the same denomitator)

0.6 = 6 / 10                                                  7/9

6/10 = 6 * 9 / 10 * 9 = 54 / 90                        7/9 = 7 * 10 / 9 * 10 = 70 / 90

The numbers which are between these numbers are ;

55 / 90 , 56 / 90 , 57 / 90 , 58 / 90 , 59 / 90, 60 / 90 , 61 / 90 , 62 / 90 , 63 / 90 , 64 / 90, 67 / 90 , 68 / 90 , 69 / 90

62 / 90 = 62 / 2 / 90 /2 =  31 / 45 

So the right answer is B.

Hope that helps :)