1.  Choose the number which is different from others in the group.
A. 13
B. 17
C. 23
D. 37
E. 73

Answer: Option C

Explanation:

Here logic is:

13 = 1 + 3 = 4 → Even number

17 = 1 + 7 = 8 → Even number

23 = 2 + 3 = 5 → Odd number

37 = 3 + 7 = 10 → Even number

73 = 7 + 3 = 10 → Even number

Hence, '23' is the correct answer.