There are total 90 twodigit numbers(10 to 99)as(9910+1=90)because 10 and 99 both included
The number of 2 digit multiples of 7 =13, these are 14, 21, 28, 35, 42, 49, 56, 63, 70, 77, 84, 91, 98.
Probability Of An Event 
P(A) = 
The Number Of Ways Event A Can Occur 
The total number Of Possible Outcomes 

Therefore, the probability that selected number is not divisible by 7 = 1 – (13/90) = 77/90.
So, option (D) is true.