The prime numbers between 0 and 20 are 2, 3, 5, 7, 11, 13, 17, and 19.
The only even prime number is 2.
If all the three numbers selected are odd, then the sum of the numbers will be odd. If one of the numbers is 2, the sum will be even.
Thus, we have to discard the cases where 2 have been selected.
If 2 is selected, the total ways to select the other two numbers will be 7C2 = 21
Total number of ways to select 3 numbers = 8C3 = 56
Total favourable cases = 56 - 21 = 35
Required probability = 35/56 = 5/8
Thus, the correct option is D.
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