To calculate Bella's velocity, we can use the formula:
\[ \text{Velocity} = \frac{\text{Distance}}{\text{Time}} \]
Here, the distance covered is 600 meters and the time taken is 2 minutes. However, we need to convert the time from minutes to seconds for consistency in units:
\[ 2 \text{ minutes} = 2 \times 60 = 120 \text{ seconds} \]
Now, we can calculate the velocity:
\[ \text{Velocity} = \frac{600 \text{ meters}}{120 \text{ seconds}} = 5 \text{ m/s} \]
Since Bella is riding directly south, we can represent her velocity as negative if we take south as the negative direction. Therefore, her velocity would be:
\[ \text{Velocity} = -5 \text{ m/s} \]
So, the correct answer is:
-5 m/s