To find the time it takes for sound to travel 2 kilometers (2000 meters), you can use the formula:
\[ \text{Time} = \frac{\text{Distance}}{\text{Speed}} \]
Substituting the given values:
\[ \text{Time} = \frac{2000 \text{ meters}}{340 \text{ m/s}} \approx 5.88 \text{ seconds} \]
Rounding this, we can say it takes approximately 5.9 seconds.
Therefore, the correct response is:
5.9 seconds