To find the speed of the car in meters per second, we need to convert both the distance and the time into the appropriate units.

1. Convert distance:
   The car travels 10 kilometers. Since 1 kilometer = 1000 meters,
   $10 \, \text{km} = 10,000 \, \text{meters}$

2. Convert time:
   The time given is 15 minutes. Since 1 minute = 60 seconds,
   $15 \, \text{minutes} = 15 \times 60 = 900 \, \text{seconds}$

3. Calculate speed:
   Speed is distance divided by time: $\text{Speed} = \frac{\text{distance}}{\text{time}} = \frac{10,000 \, \text{m}}{900 \, \text{s}} \approx 11.11 \, \text{m/s}$

Thus, the speed of the car is 11.11 m/s.

Now, rounding to two significant digits, the answer is:

b. 11 m/s

Would you like more details or have any further questions? Here are 5 related questions:

1. How do you convert units of speed from m/s to km/h?
2. What is the formula for average speed?
3. If the car continues at this speed, how long would it take to travel 50 km?
4. How would the speed change if the time were reduced to 10 minutes?
5. What is the difference between speed and velocity?

Tip: Always make sure to use consistent units when calculating speed—convert distances to meters and time to seconds for speed in meters per second (m/s).