To calculate the time it takes for Amelia to swim a race of 600 meters at an average speed of 8 meters per second, you can use the formula:
\[ \text{time} = \frac{\text{distance}}{\text{speed}} \]
Plugging in the values:
\[ \text{time} = \frac{600 \text{ meters}}{8 \text{ meters/second}} = 75 \text{ seconds} \]
So, the correct answer is b) 75 seconds.