When a pair of dice is thrown, what is the probability of the sum of numbers being odd?

Answer: Option D

Total events = 6² = 36
Sum odd = 1, 3, 5, 7, 9, 11
3 = (1, 2)(2, 1)
5 = (1, 4)(4, 1)(2, 3)(3, 2)
7 = (1, 6)(6, 1)(2, 5)(5, 2)(3, 4)(4, 3)
9 = (3, 6)(6, 3)(4, 5)(5, 4)
11 = (6, 5)(5, 6)
$$\text{Probability}=\frac{18}{36}=\frac{1}{2}=0.5$$