To find the probability of getting a sum of 5 when two dice are thrown, follow these steps:

1. List all possible outcomes when two dice are thrown:
Each die has 6 faces, so there are a total of \(6 \times 6 = 36\) possible outcomes.

2. Find the number of favorable outcomes where the sum is 5:
- (1, 4)
- (2, 3)
- (3, 2)
- (4, 1)

There are 4 favorable outcomes.

3. Calculate the probability:
The probability \(P\) is given by the ratio of the number of favorable outcomes to the total number of possible outcomes:
\[
P(\text{sum of 5}) = \frac{\text{Number of favorable outcomes}}{\text{Total number of possible outcomes}} = \frac{4}{36} = \frac{1}{9}
\]

The correct answer is: C. \(\frac{1}{9}\)