A

To find the average velocity over the interval [0, 1], we first need to calculate the displacement during this time period. The average velocity is given by the formula:
Average Velocity = \frac{Displacement}{Time Interval}.

1. **Displacement Calculation:**
Displacement can be found by integrating the velocity function over the interval.
\[ s(t) = \int v(t) \, dt = \int (2t + 3) \, dt \]
\[ s(t) = t^2 + 3t + C \]
For our purposes, we can take C = 0 (assuming initial position is 0). Now, calculate the displacement at t = 1 and t = 0:
\[ s(1) = 1^2 + 3(1) = 1 + 3 = 4 \]
\[ s(0) = 0^2 + 3(0) = 0 \]
Therefore, the displacement over the interval [0, 1] is:
\[ Displacement = s(1) - s(0) = 4 - 0 = 4 \]

2. **Time Interval:**
The time interval is 1-0=1 seconds.

3. **Average Velocity:**
Using the formula for average velocity:
\[ Average Velocity = \frac{Displacement}{Time Interval} = \frac{4}{1} = 4 \, m/s \]
Hence, the average velocity of the particle over the interval [0, 1] is 4 m/s.