A bag contains 19 balls numbered 1 through 19. What is the probability of selecting a ball that has an even number when one ball is drawn from the​ bag?

To find the probability of selecting a ball that has an even number, we first need to determine how many even-numbered balls are in the bag.

The even numbers from 1 to 19 are: 2, 4, 6, 8, 10, 12, 14, 16, 18.

Counting these, we find there are 9 even-numbered balls.

The total number of balls in the bag is 19.

The probability \( P \) of selecting an even-numbered ball is given by the formula:

\[
P(\text{even}) = \frac{\text{Number of even balls}}{\text{Total number of balls}} = \frac{9}{19}
\]

Therefore, the correct answer is:

**C. nine nineteenths**.