To convert the speed from kilometers per hour (km/hr) to meters per second (m/s), use the following conversion:

1 kilometer = 1000 meters
1 hour = 3600 seconds

The conversion factor from km/hr to m/s is:

\[
\text{Speed (m/s)} = \text{Speed (km/hr)} \times \frac{1000 \text{ meters}}{1 \text{ kilometer}} \times \frac{1 \text{ hour}}{3600 \text{ seconds}}
\]

\[
\text{Speed (m/s)} = \text{Speed (km/hr)} \times \frac{1000}{3600}
\]

\[
\text{Speed (m/s)} = \text{Speed (km/hr)} \times \frac{5}{18}
\]

For a speed of 600 km/hr:

\[
\text{Speed (m/s)} = 600 \times \frac{5}{18}
\]

\[
\text{Speed (m/s)} = \frac{3000}{18}
\]

\[
\text{Speed (m/s)} = 166.67
\]

Rounded to the nearest whole number, the speed is approximately 167 m/s.

So the correct answer is:

D. 167 m/s